Polymer interdispersions, related compositions and method of making same

ABSTRACT

Polyblend interdispersions of two or more different polymers formed at least partially in the presence of an interdispersing aid which can be polytetrafluoroethylene or ultra high molecular weight polyethylene; said blend can be chemically cross-linked with peroxides.

This application is a divison of application Ser. No. 427,213, filed9/29/82, now abandoned.

The present invention relates to polymer interdispersions, relatedcompositions, and to the methods of making same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates to application Ser. No. 427,386 of EdwardWilkus and Alexander Wu, entitled "Cables Formed With InterdispersedPolymer Compositions and Method of Making", now abandoned;

to application Ser. No 737,351 of Edward Wilkus and Alexander Wu,entitled "Crosslinked Polymer Interdispersions Containing Polyolefin andMethod of Making"; and

to application Ser. No. 426,395 of Edward Wilkus and Alexander Wu,entitled "Cables Formed With Crosslinked Interdispersed PolymerInsulation Compositions Containing Polyethylene and Method of Making",now abandoned, all assigned to the same assignee as this application andfiled concurrently herewith.

BACKGROUND OF THE INVENTION

Homopolymers have properties which are characteristic for each type ofpolymer.

Low density polyethylene generally has good film forming properties andis generally competitive with other polymeric materials in thisapplication, but it does not have high transparency or clarity in moldedapplications. By contrast, polystyrene does not have good film formingproperties, but it does have good transparency and clarity in moldedapplications.

There are numerous other illustrations of distinctive sets of physical,electrical, chemical and mechanical properties which are manifested bytypes of polymers including polyvinyl chloride, polyacetal, polyamides,polyethers, polyolefins, etc., and which are manifested by differentspecies of a polymer type as, for example, nylon 6, nylon 11, nylon 66,etc.

It is sometimes possible to combine properties of different types ofpolymers or species members by forming blends. Blends may be formedwhere it is found that the polymers are naturally compatible, i.e.,where it is found that one polymer can be mixed with or dissolved inanother polymer without the involvement of permanent chemical reaction,but with a resultant intimate uniform intermixing of the two polymers togive an apparent homogeneous composition which does not separate intoits ingredient components or segregate during ordinary processing suchas heating and conventional forming as by extrusion, molding, etc., andwhich does not segregate after processing with ordinary use or aging.Naturally occurring blends may exhibit combinations of properties whichare greater than the average of the blend ingredients for theproportions of the ingredients in the blends.

The compatibility of different polymers occurs naturally for certainpolymers and species members. For example, polyphenylene oxide polymeris naturally compatible with polystyrene, both of which are glassy-typepolymers. The polyphenylene oxide and polystyrene are the principalingredients of the family of polymeric materials in differentproportions which are available from the assignee of this applicationunder the trade designation NORYL®.

By naturally compatible is meant that the compatibility is evident andpersistant from blending which occurs readily with conventional heatingand mixing and without any modification of the ingredients of the blendand without any specific blending agents, although conventionaladditives such as antioxidants, coloring agents, etc. may be included.

Natura.lly occurring polymer blends, such as those of the NORYL familyof polymers, may exhibit a single apparent thermodynamic response whensubjected to calorimetric measurements in which specific heat ismeasured as a function of increasing or decreasing temperature. Wheresuch a single apparent thermodynamic response is found for a blend ofpolymers, it indicates that the constituents are alloyed or dissolved ineach other. The apparent thermodynamic response of a true alloy isgenerally proportional to the proportions of the constituents of thealloy.

Such exhibition of a single apparent thermodynamic response is theexception inasmuch as the polyphenylene oxide and the polystyreneconstituents of these compositions are true blends in that theconstituents are present as true solutions or alloys and the formationof true solutions of distinct types of polymers is rare and unique. Forsuch a true solution or alloy, the apparent thermodynamic response isalso distinct from that exhibited by a mixture of two types of polymerswhich are not naturally compatible and which do not form true solutionsor alloys.

Mixtures of polymers into pseudo alloys or pseudo solutions can bedetected by calorimetric measurements and are found to exhibit theseparate changes in the specific heat curve which is representative ofthe separate and unalloyed ingredients which are present.

As used herein, the term alloy blends or solution blends is meant toindicate the types of blends which exhibit the unique set of apparentthermodynamic behaviors as discussed immediately above with reference tothe NORYL® family of natural blends.

By contrast, the term polymer blends or blends is meant to refer tocompositions which, even when in very intimate state of intermixing ator near a molecular level, are not known to exhibit such distinct andunique apparent thermodynamic behavior as that exhibited by alloy blendsor true blends such as NORYL®. However, the term blends as used forcombined or mixed polymers is not intended to mean that a molecularlevel of intermixing is achieved or even achievable for a combination ofpolymers which are mixed. The degree of mixing which is achieved for agiven level of mixing effort or energy expended is largely dependent onthe affinity of one polymer of a mixture for the other polymer orpolymers of the mixture. For most polymer combinations, the affinity orcompatibility factor prevents a very intimate or molecular level ofmixing to be achieved with the level of mixing attainable byconventional industrial polymer procesing and mixing equipment.

Generally, such blends or mixtures of different types of polymers arenot readily formed and the properties of such blend compositions as canbe formed have not brought such compositions into prevalent use in theplastic industry. A higher level of blending does occur among differenttypes of rubbers and some blends are formed and used commercially in therubber industry.

Generally also, the blends of different types of polymers with rubbersare not readily formed to produce products having commercial utility.

As used herein, the term polymer or resin is intended to include bothnaturally occurring and synthetic polymers and, accordingly, to includenatural and synthetic rubbers, and polymers such as polyolefins,polyamids and other synthetic resins.

Also in general, the affinity of one polymer type for another type inthe sense of the degree of blending or dispersing which can be attainedwill depend on numerous compatibility or incompatibility factors, suchas chemical formula, chemical architecture, molecular weight, polarity,degree of crystallinity, rheological properties, first and second orderthermodynamic responses, including melting point and glass transitiontemperature, as well as on other factors.

An important element in the properties which are exhibited by a blend ofpolymer materials is the degree of intermixing which is achievable andachieved and the intimacy of the contact of one polymer material withanother in a mixture or blend. This degree of intermixing depends asindicated above on the affinity of two polymer materials for each otherbased on numerous factors discussed above and also on the energyexpended in causing the intermixing. Intermixing factors include thetemperature of processing, the level of shear developed, the pressure onthe system, the time of processing and several other factors. It alsodepends on the presence of mixing or blending aids.

The term dispersion as found in technical materials dictionaries refersto material systems having two materials present in different phases,one of which, as for example liquid, is continuous and the other ofwhich, as for example gas or solid, is discontinuous. However, accordingto Webster, the term disperse means "to break up and scatter in alldirections; spread about; distribute widely", along with alternativedefinitions. Webster defines a dispersion as "a dispersing or beingdispersed" also along with alternative definitions.

As used herein, the term interdisperse and its derivatives such asinterdispersion, means the action of breaking up and scattering of atleast one polymer material into at least another and distinct polymermaterial, while at least one of the polymer materials is undergoingflow, which results in internal shear. The term interdispersion alsomeans the product of the action. At least two distinct polymer materialsare involved in formation of an interdispersion and the compositioncontains also the dispersed fibrous interdispersing agent of thisinvention.

Surprisingly, it has now been found that certain agents are uniquelyadapted to enhance the dispersing of a first polymer into a secondpolymer to form a multipolymer interdispersion of any desired degree ofintimacy of contact of the first and second polymers.

The formation of interpolymer interdispersions pursuant to thisinvention has been demonstrated to be feasible for polymers which havevery little or no affinity for each other.

Polymer affinity factors may be classified according to a number ofdifferent groupings. For example, some polymers such as polyethylenesare more highly crystalline and are in a class of more highlycrystalline polymers generally having a sharper softening or meltingpoint. Low density polyethylene is about 55 to 60% crystalline and highdensity polyethylene is over 90% crystalline. Others are classified asglassy polymers and these soften over a wider temperature range. Thereare essentially no naturally compatible or easily formed binary blendsof highly crystalline polymers such as polyethylene with the more glassypolymers such as polyvinyl chloride.

However, more highly crystalline polymers can be interdispersed with themore glassy polymers using the interdispersing agent of this invention.For example, low density polyethylene has been interdispersed pursuantto this invention with polyvinyl chloride, although it is widelyrecognized in the art that low density polyethylene and polyvinylchloride are extremely incompatible. By itself, this demonstratedinterdispersability of low density polyethylene directly with polyvinylchloride with the aid only of an interdispersion agent is deemed todemonstrate an extraordinary and remarkable interdispersing capabilityof the agent. The product formed is an interdispersion of each polymerin the other and the degree of dispersion achievable can make thecomposition comparable to a blend.

Other polymers are classified in a group of more amorphous materials orrubbery polymers. Generally, members of the amorphous group such asethylene propylene rubber are not naturally compatible with either themore glassy polymers such as polyvinyl chloride nor with the more highlycrystalline polymers such as polyethylene.

An important attribute of the agent is that it permits interdispersingof distinctly different polymers to any desired degree, but at the sametime, interlocks the interdispersed polymers as explained more fullybelow so that they resist separation even though the degree ofinterdispersion is less than at the molecular level and, in fact, low ona relative basis, i.e., relative to the tendency of the components of amixture to separate responsive to separating influence such as selectivesolvent action.

However, with the aid of the interdispersing agent of this invention,interdispersions of highly crystalline polymers may be formed with themore glassy polymers. For example, ethylene propylene rubber polymer canbe and has been blended with high density polyethylene.

Also, the highly crystalline polymers can be blended with the moreglassy polymers as, for example, polystyrene, which is a largely glassypolymer, has been interlocked as a blend with Delrin, which ispolyacetal and is a highly crystalline polymer.

Also, some polymers are classified as more highly polar and otherpolymers are classified as non-polar. Generally, more highly polarpolymers do not blend readily and naturally with non-polar polymers.However, more highly polar polymers such as polyvinyl chloride may beinterdispersed with non-polar polymers such as high or low densitypolyethylene.

By naturally occurring blends as used herein is meant blends which areformed readily with ordinary and conventional heating and mixing andwhich persist due to the inherent compatibilities of the components ofthe blend. Such compatibility may be due to similar molecular andchemical structure. For example, chlorinated polyethylene blends to adegree with natural rubber or with styrene butadiene rubber as pointedout in U.S. Pat. No. 4,262,098.

However, some polymers which may appear to have similar molecular andchemical structure do not blend naturally, i.e., readily with ordinaryheating and mixing and without the aid of blending agents. For example,high density polyethylene does not blend readily and easily with lowdensity polyethylene by ordinary and conventional heating and mixing.Nevertheless, high density polyethylene is interdispersable with lowdensity polyethylene at low levels of energy input to forminterdispersions with the aid of the interdispersing agent as providedpursuant to the present invention.

It will be understood that the formation of certain blends may bebrought about by application of higher energy processing conditions thanare ordinarily used and ordinarily preferred in forming polymercompositions.

For example, if high temperature are employed in an effort to blend highdensity polyethylene with low density polyethylene, it is probablyfeasible to find a set of blending conditions at which an apparent blendwill form. The set of conditions can involve high temperature, highpressure, high level of mechanical energy input or agitation and otherhigh energy inputs.

However, as a general rule, a polymer material has a useful lifeexpectancy which is related to the thermal and other energy historywhich it has experienced in the processing and fabrication stage.Accordingly, it is desirable generally to process a polymer andfabricate an article from a polymer at a lower set of energy inputconditions and particularly at lower temperatures and lower time attemperature in order to preserve as much as possible of the inherentuseful life expectancy of the polymer.

To avoid the harsh processing conditions which may be needed to formapparent blends and to gain the advantage of sets of properties whichare not available in homopolymers, copolymers have been formed bychemical techniques. Accordingly, to overcome the incompatibility ofdifferent polymers, and in order to make compositions available whichhave combinations of properties which are not found in any of theindividual polymers, chemical combinations of different monomers aremade under suitable polymerization conditions to form copolymers.

For example, ethylene monomer, principally used in making polyethylene,and propylene monomer, principally used in making polypropylene, can becopolymerized under suitable conditions to make ethylene-propylenecopolymer or ethylene-propylene rubber

Similarly, the monomers used in making polyacrylonitrile, polybutadieneand polystyrene as distinctive individual polymers can be copolymerizedto form ABS copolymer, or acrylonitrile-butadiene-styrene copolymer.

Generally, a different set of polymer properties are obtained in thecopolymers formed by copolymerization of the distinct monomers incombination than are obtained by separately polymerizing the individualmonomers to their respective homopolymers. For example, while neitherpolyethylene nor higher molecular weight polypropylene has distinctlyrubbery properties, some ethylene propylene copolymers have distinctlyrubbery properties.

The cost of copolymers is generally substantially higher than the costof the homopolymers made from the individual monomers.

Polypropylene and low density polyethylene are at best poorly compatiblepolymer species in that only small percentages, if any, of either onecan be blended into the other through conventional blending methods andmeans. At higher concentrations, the species are incompatible and do notform homogeneous blends.

Surprisingly, it has now been found that using conventional mixing andblending practice and equipment, interdispersions of normallyincompatible ratios of polyethylene and polypropylene, is made feasibleby the use of a small amount of an interdispersing agent pursuant tothis invention.

The number of copolymers which can be formed by copolymerizationreactions is limited. This is partly because the polymerizationconditions, the polymerization catalysts, and the polymerizationmechanism differs for many polymer species. For example, not allmonomers, such as olefin monomers which can be polymerized by one of the"addition" type mechanisms, can be copolymerized with monomers, such asesters, which are polymerized by "condensation" type mechanisms.Accordingly, it is not feasible to form copolymers by copolymerizing allcombinations of selected monomers.

Different polymer species, the distinct monomers of which could not beformed into copolymers by presently existing technology, cannevertheless be interdispersed in each other with the aid of theinterdispersing agents of this invention to achieve combinations ofproperties which have not heretofore been available.

Copolymers are prepared commercially in certain preferred monomer ratiosto give the copolymer formed preferred combinations of properties. Forexample, ethylene vinyl acetate copolymer prepared from the ethylenemonomer and the vinyl acetate monomer will have a more rubbery set ofproperties if the ratio of ethylene monomer to vinyl acetate monomer isat one value, for example, 25% of vinyl acetate, and will have a lessrubbery set of properties if the ratio of monomers is at another value,for example, 3% vinyl acetate.

However, it is not commercially feasible to alter the ratio of monomersfor each specific end use application to which the copolymer may be put.Rather, the commercial product is produced with a certain number ofmonomer ratios, and the end user must try to adapt the commerciallyavailable materials to the end use contemplated. Further, for those setnumbers of copolymers which are produced, the supplier and wholesalermust stock all or most of them to satisfy his customer's needs.

However, it is feasible to modify the properties of interdispersions ofotherwise poorly compatible or incompatible homopolymers byinterdispersing two incompatible polymers with the aid of aninterdispersing agent of this invention in any desired or selected ratioof homopolymers, and to achieve the properties which are the result ofsuch interdispersing in any such selected ratio.

Moreover, such dispersing can be achieved without the aid of chemicalpolymerization equipment and can be accomplished for most binary polymersystems through use of existing and commercially available mixing andprocessing equipment such as rubber mills, plastic mills, extruders,high intensity mixers and the like.

Accordingly, this invention makes possible the custom interdispersing bythe end user of different combinations of polymers to achieve a desiredset of properties for particular end uses to a degree not previouslypossible.

Further, the invention is not confined to the interdispersing of binarysets or combinations of homopolymers, but extends to the interdispersingof tertiary combinations of homopolymers, quaternary combinations ofhomopolymers, and other multinary combinations of homopolymers in allratios and proportions. Multinary as used herein means sets of two ormore members in combination without limitation as to any upper number ofmembers and includes sets of five or six or more homopolymer members.

In addition, interdispersions of combinations of homopolymers withincompatible or poorly compatible copolymers can be made in binary setsand/or multinary sets without limitations as to the number of members ina set nor as to proportions nor as to the number of homopolymers ascontrasted with copolymers in the set. On the same basis, multinary setsof copolymers can be combined and interdispersed in all ratios andproportions.

Another form of copolymer which is even more difficult to produce thanthe ordinary random copolymer and which is also used in efforts to blendpolymers is the block copolymer form. This form has a set of a firstmonomer species such as "A" polymerized in a first block "AAAAAA" andanother set of a second monomer species "B" polymerized in a secondblock "BBBBBB". Repeating alternate blocks gives the polymer a formwhich may be represented as follows:

    AAAAA BBBBB AAAAA BBBBB AAAAAA

One set of such polymers which has been used widely is the set which hasalternating blocks of polystyrene and polybutadiene and which are soldcommercially by the Shell Oil Company under the designation Kraton.

The Kratons are thermoplastic rubbers and have a combination ofthermoplastic properties, due to the presence of the blocks ofpolystyrene, and rubber properties, due to the presence of blocks of thepolybutadiene.

However, pursuant to the present invention, interdispersions ofdifferent polymers, such as polystyrene and polybutadiene, can be formedto yield interdispersed compositions having unique sets of properties.

The properties of polymer species occur in sets in the sense that onepolymer species has a certain specific density, softening temperature,izod impact, tensile strength and other physical, chemical, electrical,mechanical and thermal properties, all of which are subject tomeasurement and which can accordingly be quantified. The sets ofproperties of the different polymers and different members of familiesof polymers such as the polyolefins have been measured and are known.

It is the current practice in the plastics industry that when a choiceis made of a polymer for a particular end use, it is made on the basisof the material and processing cost and on the basis of theappropriateness of a particular set of properties for the intended enduse.

When an interdispersion of polymers is made pursuant to the presentinvention, although the starting sets of properties of each individualingredient polymer is known, not all of the combination or set ofproperties which will result from the interdispersing is readilyapparent or highly predictable. For example, as is pointed out below inExample 1, a material which is known to have high flexibility, such as arubber, may be chosen as one constituent of an interdispersion to lendflexibility to the interdispersion. Where increased toughness is sought,a second although normally incompatible constituent may be selected toimpart toughness or abrasion resistance to the interdispersion. However,although it is expected that an interdispersion can be formed pursuantto the present invention having some combination of flexibility andtoughness properties, there is no way of predicting quantitatively justwhat properties will result from the intimate interdispersion with theinterdispersing agent of this invention of materials which are otherwiseincompatible or poorly compatible under a given or a particular set ofconditions used in forming a particular interdispersion.

In Example 1, the properties found and reported are not the propertiesonly of the interdispersion of high density polyethylene with ethylenepropylene rubber. In fact, almost no properties of this composition weremeasured although several were observed, i.e., the material handled welland processed well and extruded well as contrasted with the inferiorobserved properties of the material of Example 2 which did not containthe dispersing agent of this invention, which did not handle well orprocess well or extrude well.

Considering now the interdispersing agents of this invention, it has nowbeen discovered that very long chain polymers of polytetrafluoroethyleneand of polyethylene of very high and ultra high molecular weight exhibita unique and unexpected behavior in inducing the interdispersion of afirst polymer into a second and distinct polymer as the polymers aresubjected to a motion which induces shear within the polymers.

The term interdispersion as used herein is meant to include thedispersion of a first polymer into a second polymer as well as thedispersion of the second polymer into the first either simutaneously orsequentially and to include an interdispersion of both polymers intoeach other simultaneously. For purposes of this invention, either thefirst and/or second polymer may be a homopolymer, copolymer, orcombination of polymers, either naturally occuring blends orcombinations of poorly compatible or incompatible polymers induced intointerdispersions by the interdispersing agents of this invention.

These interdispersing agents have been found to be effective incombining distinct polymers into interdispersions with a generally lowerlevel of energy input than is needed to form blends which have anequivalent degree of intimacy of contact of the constituents as can beformed in the absence of the interdispersing agents of this invention.

For example, as is pointed out in Example 31 below, it has been foundthat an apparent blend of polyethylene and polystyrene can be formed ona mill at a temperature of 310° F. However, at 240° F., the sameingredients do not enter an apparent blend to any observable extent.However, at 240° F., the polyethylene and polystyrene can beinterdispersed to form a composition which has an appearance on the millclosely resembling the apparent blend formed at the higher temperatureof 310° F. The interdispersing agents can also form interdispersions ofcombinations of polymers which do not form apparent blends at higherenergy levels as, for example, at higher temperatures or other higherenergy input levels.

As understood by the applicants, the unique ability of theinterdispersing agents to form interdispersions of incompatible polymersand to form interdispersions of poorly compatible polymers at lowerenergy levels is related to the ability of these agents to extend intofibrous form and to disperse through the polymer in this fibrous form asthe host polymers undergo internal shearing action by the working orprocessing of the polymers.

The applicants herein are not the first ones to discover the uniquemorphology of the polytetrafluoroethylene which has now been discoveredby the applicants to be an intrdispersing agent. Nor are they the firstones to discover the influence on a single polymer of fibrouspolytetrafluoroethylene.

U.S. Pat. No. 3,132,116 issued in the name of one of the inventors ofthis application and assigned to the assignee of the subjectapplication, discloses that if a silicone polymer is blended with fillerand other conventional ingredients in the presence of a minor amount oftetrafluoroethylene polymer, the characteristic tackiness of the blendedmixture is dramatically reduced, and, in addition, that the propertiesof elastomers derived therefrom are improved, compared to elastomersderived from such mixtures free of polytetrafluoroethylene.

By contrast to the subject matter of the U.S. Pat. No. 3,132,116 whichdeals only with a treatment of a single polymer, i.e., treatment ofsilicone polymer with PTFE, the compositions of the present inventioncomprise at least two polymers of distinct properties to whichpolytetrafluoroethylene is added, and the interdispersions of thesedistinct polymers into each other with the aid of the PTFE.

In addition, the PTFE addition has been found to make important changesin the properties of the combined polymers of this invention to which itis added as, for example, the rate at which the interdispersed polymerscan be dissolved in comparison to the rate at which a blend or mixtureof the same polymers can be dissolved in the absence of PTFE.

A significant advantage of the present invention is that it makespossible for the first time for many binary and other multinary systemsof polymers a very effective and efficient means and method for bringingtogether in very intimate intermixed contact or intimateinterdispersions polymers which cannot otherwise be so easily intimatelyblended and intermixed. To achieve an equivalent degree of intimacy ofintermixing would otherwise require expensive or cumbersome orextraordinary means and measures, and as is pointed out above, suchextraordinary measures can detract from the combined properties of thepolymers which are combined.

It should be pointed out that because of the fibromorphous character ofthe dispersing agent of this invention, the dispersions which are formedhave coherency and integrity of structure even though the extent ofinterdispersion is brought to an optimum degree.

Generally, an optimum degree of dispersion can be achieved in arelatively short processing time, which may be of the order of minutesor hours, depending on the degree of internal shear induced in thepolymers. For the processing of a relatively small quantity of acombination of polymers as, for example, low density polyethylene andPVC on a small plastic mill, each of which polymers is millable at thetime of processing, an effective interdispersion can be achieved in aperiod of about 10 minutes and a higher degree of interdispersion can beachieved in 20 or 30 minutes where the degree of interdispersion ismeasured by rate of burning of a horizontal strip of the productinterdisperion. Clearly, however, the degree of interdispersion can becontrolled as, for example, by controlling the time and temperature ofmilling and intensity of agitation.

An optimum degree of interdispersion is deemed to result in an intimatecontact of the different polymers at a level approaching a molecularlevel although the applicants have no direct evidence of such molecularlevel of contact and do not wish to be bound by the accuracy of thisprognosis.

But the inventors have found that for numerous compositions which havebeen formed on a mill, for example, without the dispersing agents ofthis invention, the milled mixture does have less coherency andintegrity when processed under a given set of conditions for a giventime and temperature as compared to the coherency and integrity of acomposition of the same ingredients processed under the same set ofconditions for the same time with the aid of an interdispersing agent ofthis invention.

This rapid development of integrity of a composition of two normallyincompatible polymers is dramatically demonstrated when quantities ofthe two polymers are placed on a mill and subjected to milling actionfor a given period of time. As illustrated by the examples below, wherethe two polymers are milled for a given time and temperature, frequentlythere is no evidence of interdispersing of blending or intimate mixingof the two polymers.

If a first half of the milled composition is then removed from the milland the dispersing agent of this invention is added to the second halfof the composition remaining on the mill, a very rapid and dramaticinterdispersing of one polymer into the other will be observed in thesecond half of the composition.

If this second half polymer dispersion is then removed from the mill andthe first half of the composition, free of the dispersing agent, isreturned to the mill, it will be observed that the milling can becontinued for a significant time beyond that which resulted in formationof the interpolymer dispersion of the second half composition containingthe dispersing agent.

OBJECTS OF THE INVENTION

It is accordingly one object of the present invention to provide broadspectrum interdispersing agents for dispersing normally incompatible andpoorly compatible polymer materials, including organic and inorganicpolymers.

Another object is to provide a broad spectrum method for dispersingnormally incompatible and poorly compatible polymer materials includingorganic and inorganic polymers.

Another object is to provide novel compositions comprising a broadspectrum of interdispersions of normally incompatible and poorlycompatible polymer materials, including organic and inorganic polymersand polytetrafluorethylene dispersing agent.

Another object is to provide articles incorporating at least one of abroad spectrum of interdispersions of normally poorly compatible orincompatible polymer materials, including organic and inorganicpolymers.

Another object is to provide a method to enhance the homogeneousincorporation into polymer base materials of higher concentrations ofcertain polymer additives, the incorporation of which is restrictedbecause of poor compatibility.

Another object is to provide homogeneous polymer base material havingpolymeric additives therein in higher concentrations than normallyfeasible based on limited compatibility of the polymer of the additiveand the polymer of the base material.

Another object is to provide articles made of polymer base materialshomogeneously blended with polymeric additives which are normally poorlycompatible with the base material.

Another object is to include curing agents in the curable novelcompositions of the present invention.

Another object is to provide curable novel compositions of the presentinvention and to cure such compositions.

Another object is to provide novel articles which include cured novelcompositions of the present invention.

Another object is to provide molded articles which include the novelcompositions of the present invention.

Another object is to provide injection molded articles which includecertain novel compositions of the present invention.

Another object is to provide novel sheet articles which include certainnovel compositions of the present invention.

Another object is to provide novel film products incorporating the novelcompositions of the present invention.

Another object is to provide novel filament and fiber productsincorporating novel compositions of the present invention.

Still another object is to provide polymeric additives containingpolytetrafluoroethylene dispersed therein, which additives can be easilyblended and dispersed in relatively low percentage concentrations intodifferent polymers.

Another object is to make possible the incorporation into polymer basematerials of polymeric additives which are not normally incorporablebecause of incompatibility of the polymer base of the additive and thepolymer base of the material.

Another object is to provide polymer base compositions having polymericadditives homogeneously interdispersed therein, which additives arenormally incompatible with the polymer base composition.

Another object is to provide articles which include polymer basecompositions having polymer base additives homogeneously interdispersedtherein, which additives are normally incompatible with the polymer baseof the composition.

Another object is to provide novel compositions comprising a multinaryset of polymers dispersed together with the aid of finely fibrouspolytetrafluoroethylene, ultra high molecular weight polyethylene, orhigh molecular weight polyethylene and combinations thereof.

Another object is to interdisperse together in a single stepcombinations of three or more polymers, which under conditions whichhave required more than one step heretofore, by including in the singleinterdispersing step the dispersion of finely fibrouspolytetrafluoroethylene, ultra high molecular weight polyethylene orhigh molecular weight polyethylene into the contituents of the blend.

Other objects and advantages will be in part apparent and in partpointed out in the description which follows.

BRIEF SUMMARY OF THE INVENTION

In one of its broader aspects, objects of the invention may be achievedby dispersing polytetrafluoroethylene, ultra high molecular weightpolyethylene or high molecular weight polyethylene in fine filamentaryform into a multinary set of poorly compatible and/or incompatiblepolymers to form an interdispersion of the polymers to a desired degreeof intimacy of contact of the interdispersed set of polymers.

Novel compositions may be formed pursuant to the present invention andcomprise two or more poorly compatible or incompatible polymerscontaining an amount of fibrous polytetrafluoroethylene, ultra highmolecular weight polyethylene or high molecular weight polyethyleneeffective to at least partially interdisperse the polymers together.

In another of its aspects, the objects may be achieved by providing asecondary treatment for a composition containing two interdispersedpolymers with fine filamentary polytetrafluoroethylene, ultra highmolecular weight polyethylene or high molecular weight polyethylenedispersed therein.

DETAILED DESCRIPTION

It has been discovered that normally incompatible and, accordingly,normally unblendable polymers may be interdispersed with the aid ofconventional polymer processing apparatus and methods which generateinternal shearing action in the polymers where a relatively smallconcentration of polytetrafluoroethylene is incorporated in fibrous formin the polymer materials being processed.

It has now been discovered that two polymers which are not normallyblended when heated and mixed in conventional equipment used for thispurpose at a given set of conditions can be made to interdisperse to adesired degree of intimacy of contact by the addition of a small amountof polytetrafluoroethylene to the material and by the same conventionalheating and mixing equipment under the same set of conditions.

The ability of the polytetrafluoroethylene to induce the interdispersionof polymer materials which are not normally blendable under givenconditions in conventional heating, mixing and blending apparatusappears to be related to the formation of fine fibers or filaments ofthe polytetrafluoroethylene as the material is being heated andagitated, mixed to form an interdispersion in such conventionalapparatus.

When most thermoplastic materials are heated, their state is changedfrom the more solid state in which they are normally used inconventional articles to a more plastic state in which they can be madeto flow under the stress applied by the apparatus in which they areprocessed. The result of flow of one layer of polymer over and againstanother layer is a shearing action within the body of the polymermaterial itself, and this shearing action can be of different degrees ofintensity depending on the state of the polymer and the level of energyemployed in causing differential relative movement of the portions ofpolymer being processed. It is this shearing action of the polymer whilein the plastic state which is responsible for such agitation as formsblends of compatible or normally blendable materials.

It has been observed that powdered polytetrafluoroethylene or PTFE whenadded to fluxing polymer on a roll mill tends to be stretched out intofilamentary or fibrous form.

Such stretching out of PTFE into fibers when undergoing shear in anorganopolysiloxane has been described in the prior art. The U.S. Pat.No. 2,710,290 to the same assignee as the subject application describesthe formation of fibers of PTFE in silicone polymers. According to thispatent, compositions of organopolysiloxane polymer and thepolytetrafluoroethylene particles which have been sheared into fibersare said to have improved tear strength.

It has been observed by the applicants that a bead of polymer in the nipof the rolls of a small plastic mill has a generally round andundisturbed surface when a polymer which is free of PTFE is fluxing onthe mill. However, when this same bead of polymer is observed after theaddition of PTFE, there is a distinct tendency for longitudinallyoriented folds or nodes to form in the upper surface of the bead andthere is a distinctive formation of filaments of PTFE which bridges thenodes and appear to the unaided eye as fibers.

The powdered polytetrafluoroethylene or PTFE material used in connectionwith this invention is a fine powdered polytetrafluoroethylene which iscurrently commercially available from the E. I. Du Pont de Nemours andCompany of Wilmington, Del., hereafter referred to as Du Pont Company,under the trade designation Teflon 6, also sometimes abreviated as T-6.

The Teflon 6 material may have some similarities, based on similaritiesof its observed behavior in homopolymers, such as high density or linearpolyethylene, to a polytetrafluoroethylene described in a U.S. Pat. No.3,005,795 assigned to the same Du Pont Company. Polytetrafluoroethylenesand other fluorocarbons which are not susceptible to the formation ofthe extensive fibrous filaments and which do not accordingly undergofillibration are not deemed to be interdispersing agents which forminterdispersions of distinct polymers pursuant to this invention. Whileit is not known whether the polytetrafluoroethylene which was obtainedfrom the Du Pont Company under the trade designation Teflon 6corresponds in its structure and manifestations to that described in theDu Pont patent, the Applicants here have found the Teflon 6 to beeffective as an interdispersing agent as described above and as setforth in the examples below and have associated the ability of theTeflon 6 polytetrafluoroethylene to be dispersed in fibrous form inpolymeric media with the changes in properties manifested by the media,including the intimate interdispersing together of polymers underconditions under which they would not blend or otherwise combine into ahomogeneous composition.

It has further been observed that the fibrous nature of thepolytetrafluoroethylene interdispersing agent causes a binding togetherof the interdispersed polymers when they are in the early stages ofinterdispersion. For example, it has been observed that when twoincompatible polymers are interdispersed with the aid of thepolytetrafluoroethylene and the material is stretched into a sheet orfilm when the degree of dispersion is of a lower order, there is atendency of the material to display a network of fibers and quasiparticles. The particles are not clearly identifiable as such, butappear to be closely linked and somewhat conforming to adjacentparticles. However, at an early stage of the interdispersing, thepolymers being interdispersed may display a much lower resistance tobeing stretched in a direction generally perpendicular to the "machine"direction, that is, the direction in which the material is initiallybeing worked and stretched into film, as on a plastic mill. Further, thestretching normal to the machine direction can result in opening up ofseams in the sheet material and very close observation of such seamswill reveal an extensive array of fine fibers which are stretched as theseam is opened.

A subsequent pull on the sheet in the machine direction while in readilyworkable or plastic state can result in an apparent closing up of theseams and restoration of the appearance of a sheet material.

However, it is deemed evident from this behavior of certain samples ofincompatible polymers which are partially interdispersed that the fibersperform an interlocking or binding function in binding together withfibers of the polytetrafluoroethylene the discrete materials of theincompatible polymers.

While such phenomena is observable on a macro scale at an early stage ofinterdispersion, it is deemed to persist in the micro scale so that theincompatible polymers are not only dispersed into each other, but areeffectively interlocked by the fibrous interdispersing and interlockingagent.

Evidence of such interlocking is found when an effort is made toseparate the elements of the interdispersion by solvent action.

In this connection, as pointed out in Example 31B below, an apparentblend of polyethylene and polystyrene formed by heating and mixing thesepolymers at 310° F. was readily dissolved in boiling toluene in a periodof less than 5 minutes. However, essentially the same composition ofpolymer ingredients in the same ratio prepared in the same manner at thesame temperature but containing 1.8 parts of fibrous PTFE as set out inExample 31B did not dissolve when left in boiling toluene for over anhour and, in fact, about one-third of the composition remained after theboiling in toluene for over an hour.

In fact, it is the concept of the Applicants herein that similar bindingtogether of distinct polymers into a bound or interlockedinterdispersion can be accomplished by the other fibromorphous materialwhich have a morphology similar to that of polytetrafluoroethylene andwhich can be distributed in fine fibrous form into polymer media by theinternal shearing action of the polymer strata as the polymer is workedor masticated as it is in milling equipment, high intensity mixingequipment and similar conventional polymer masticating and shearingequipment. Ultrahigh molecular weight polyethylene and very highmolecular weight polyethylene are deemed to be such interdispersingagents for forming interdispersions of polymers.

Accordingly, the influence of the finely distributed fibrous agent onpolymers is deemed herein to be at least partly a physical phenomena, bywhich the fibromorphous agent is distributed as fibers by shearing orsimilar action into finer and finer states of subdivision in diameterwhile still retaining very long lengths relative to the diameters, andalso by which the fine fibers associate with and bind or interlockdistinct polymers into an intimate interlocked interdispersion underconditions which such distinct polymers would not form blends orintimate interdispersions. Also, if the set of distinct polymers does atleast partially blend, the interdispersing agent interlocks thecomponents of the blend in the relationship discussed above, forexample, relating to the reduced solubility of the components of theresultant composition.

The intimate intermixing or interdispersion of extraordinary diversesets of polymers is an extremely valuable tool in its own right andprovides many valuable new compositions of matter which have valuableand persistant combinations of properties as is brought out in thediscussion and examples below. Such interdispersion of diverse polymerspursuant to this invention is also valuable because it permits othermeasures to be taken to preserve and enhance such intimately intermixedcompositions or to permanently modify the polymer affinities and/orproperties while in such interdispersed state.

For example, in Example 1 below, it is taught that a binary combinationof polymers which are not blendable into an intimate admixture employingconventional means can be and have been interdispersed pursuant to thepresent invention and once they are so blended, they can then be furtherpermanently changed in their relationship by crosslinking.

In the case of Example 1, the crosslinking is of a high degree so as topermanently alter the form of the thermoplastic of the interdispersedcomposition to a thermoset form. Once the composition is thermoset astaught in Example 1, it is no longer feasible to modify the form of thematerial, which may for example be in the form of a layer simply byheating and working it in its plastic state. This is because the highdegree of crosslinking alters the plastic state of the composition andconverts it from the thermoplastic state, which it was in when the layerwas formed, to a thermoset state in which the layer will remain duringthe useful life of the layer.

However, it is evident that a composition such as that of Example 1which can be crosslinked to a higher degree by including higherpercentages of crosslinking agent, can also be crosslinked to a lowerdegree to induce co-grafting by including lower percentages ofcrosslinking or co-grafting agents. For example, the composition ofExample 1 below contained about 3 parts of crosslinking agent. However,use of lesser amounts of crosslinking agent in the order of 1 part or0.5 parts, as taught in Example 36, or 0.1 part or 0.001 part or less toinduce co-grafting is also feasible.

By co-grafting as used herein is meant the chemical linkage of a firstmolecule of one polymer of an interdispersion to a different molecule ofa second polymer of the same interdispersion so that the two distinctmolecules are chemically linked or grafted. A crosslinking agent such asa peroxide can be a co-grafting agent when present in an interdispersedpolymer composition such as that provided by the present invention in aconcentration which permits the chemical binding of the differentmolecular species without depriving the blend of its thermoplasticproperties. In this co-grafting application, the use of the PTFEinterdispersing agent is deemed to be preferable to the use of the ultrahigh molecular weight polyethylene or very high molecular weightpolyethylene interdispersing agents because the PTFE agent is lesslikely to enter a crosslinking reaction with other polyolefins of theinterdispersed composition.

Further, the present invention is not limited to secondary treatment ofthe novel compositions of this invention as by peroxide crosslinking.

Other crosslinking or co-grafting agents and crosslinking means may beemployed. For example, radiation crosslinking or radiation co-graftingmay be employed and the radiation crosslinking can be done at differentlevels to impart a higher or lower degree of crosslinking or co-graftingto the intimately intermixed and interdispersed compositions of thepresent invention. For co-grafting the ratio of polymer molecules in abinary interdispersion is preferably about 50/50 so that the probabilityof grafting a first polymer type to a second polymer type by theco-grafting is high.

In addition, in the secondary treatment of interdispersions of thisinvention, other crosslinking methods, agents and systems can beemployed as, for example, the crosslinking according to the commercialprocess known as the Sioplas process as shown in Examples 37, 40 and 41below.

Accordingly, one feature of this invention is to provide a primaryintimate admixture and interdispersion of normally incompatible orpoorly compatible polymer materials with the aid of fibrous PTFE asdescribed in the examples below and to then subject the interdispersionto a secondary treatment, such as the co-grafting or partialcrosslinking secondary treatment also described in the Example 36 belowto alter and modify the properties of the interdispersed ingredients andof the interdispersed composition.

In the secondary processing of primary interdispersions prepared tocontain the fibrous PTFE, one object is to take advantage of the factthat the primary interdispersion in fact exists for the first time orexists at temperatures and under conditions at and under which suchcompositions had not previously existed.

For example, it had not previously been feasible to interdispersepolyethylene and polypropylene in an intimate and enduringinterdispersion. Because such a composition can be prepared in anyproportion pursuant to the present invention, the secondary processingof such primary interdispersions has now become feasible pursuant to thepresent invention. It is now possible to apply a wide variety ofsecondary treatments to such primary interdispersions also pursuant tothe present invention.

One very important difference in the secondary treatment is the possibleapplication of dynamic secondary treatment under conditions notpreviously available. For example, since polyethylene and polypropylenecould not be interdispersed or blended into apparently homogeneouscompositions at conventional processing conditions in all proportionspreviously, the present invention makes possible the secondaryprocessing of such a primary interdispersion while the interdispersionis being fluxed in conventional processing equipment. For example, aprimary interdispersion of a polyethylene and polypropylene in a 50/50ratio, or of other similar interdispersions of the present invention ona mill roll may be subjected to intensive radiation, such asultra-violet or other photoradiation, while it is banded on a roll andis being fluxed on the roll.

Similarly, such a primary interdispersion can be included in a highintensity mixer and can be heated in the mixer to induce reaction with achemical co-agent, such as the triallyl cyanurate agent used in severalof the examples below, with peroxide co-grafting agent. A co-agent, suchas triallyl cyanurate, is one which assists and enhances thecrosslinking which is induced by a crosslinking agent, such as peroxide,in a polymer to be crosslinked, such as a polyolefin polymer.

One feature of the present invention which must be appreciated torecognize the extraordinary breadth of primary and secondary processingis that the PTFE interdispersing agent used in forming many primaryblends of this invention is one of the most chemically inert materialsknown to polymer science.

Because of the inertness of the fibrous PTFE, a very wide variety ofcrosslinking, co-grafting and other agents and methods can be employedwithout impairing the effectiveness of the fibrous PTFE as a primaryinterdispersing agent.

U.S. Pat. No. 3,005,795 patent to Du Pont teaches that the applicationof very high levels of radiation of the order of 106⁶ rep. or more of 2mev. electron radiation directly to PTFE prior to filibration of thePTFE changes the fiber forming properties of the PTFE. Such highirradiation of the fiber forming PTFE can, according to the U.S. Pat.No. 3,005,795, lead to degradation of the PTFE and reduce theeffectiveness of the PTFE in modifying the properties of the singlepolymers. However, pursuant to the present invention, such secondarytreatment as radiation as by high speed electrons can beneficiallyco-graft distinct polymers which are first formed into a primaryinterdispersion with the aid of the fibrous PTFE, particularly, in adynamic mode as discussed above, e.g., while fluxing on a mill, highintensity mixer, etc.

Accordingly, if some deterioration of the primary interdispersing agentoccurs as the interdispersion is made more permanent and persistant bythe application of secondary processing, the net result can be aninterdispersion having a more desirable set of properties based onchemical linkage of the diverse molecular components of theinterdispersion, even though the agent which made the primaryinterdispersion possible is involved in or even impaired by thesecondary processing. For example, the high molecular weightpolyethylene and ultra high molecular weight polyethyleneinterdispersing agents of this invention can be expected to enter intothe crosslinking phenomena occurring in an interdispersion when aperoxide crosslinking agent is employed to crosslink two polyolefinssuch as ethylene propylene rubber and low density polyethylene as setforth in Example 53 below.

For a great number of combinations of polymers, it has simply not beenfeasible heretofore to attempt secondary processing to improve theproperties and permanence of a primary blend because without the presentinvention, the formation of the primary blend under a favorable set ofconditions as a very intimate and persistant admixture of diversepolymers, which primary blend can undergo very extensive processingwhile retaining its primary blend integrity, has not been feasible byany other known manner or means. However, such secondary treatment ofcombinations of extremely diverse polymers is made possible pursuant tothe present invention because it is possible to form such very intimateand persistant admixtures as interdispersions by use of theinterdispersing agents of the present invention.

Another advantage of the interdispersed polymeric compositions of thepresent invention is that the interdispersions of sets of distinct anddiverse polymers may be formed although the concentration of the fibrousPTFE necessary to form such interdispersed polymeric compositions is sosurprisingly low. The 1.8 parts of PTFE used in most examples below isnot a lower limit of PTFE, but was adopted to provide a basis forcomparison of results obtained in interdispersing different sets ofpolymers and is not intended to indicate a minimum, maximum or optimumconcentration of PTFE for any intended purpose or for any polymerinterdispersion system where polymer interdispersion system as used hereis intended to include a multinary combination of distinct polymers inany set of proportions and with any concentration of dispersed fibrousPTFE.

Concentrations of interdispersing agent from a very low fractionalpercentage of 0.001% or less to percentages which can be accepted by acomposition, without loss of desirable properties of a composition andranging up to 20% and higher, can be employed as disclosed in Example27C is within a desirable range.

Where concentrates are employed higher percentages up to about 35% ofPTFE dispersed within an interdispersion of polymers is contemplated asan operable upper range.

Because of economic factors, i.e., the cost of the interdispersing agentsuch as fibrous PTFE, it is preferred to employ only enough of such aninterdispersing agent to accomplish the degree of interdispersion ofwhich is necessary for a particular application. From the examplesbelow, it is evident that to form most interdispersions of distinctpolymers in a 50/50 ratio, a concentration of the PTFE fibrousinterdispersing agent of less than 2% is sufficient.

Where the ratio of polymers interdispersed is lower, i.e., 20/80; 10/90;30/70, etc., and the interdispersing agent can be effectively includedin the polymer present in the lower concentration, an overallconcentration of interdispersing agent well below the 2% level can beemployed and still achieve sufficient interdispersion. For example, if a5% concentration of PTFE is first included into a polymer ingredientsuch as silicone rubber and the silicone rubber is to be interdispersedinto a polyolefin containing no PTFE dispersed therein in a ratio of 10parts of silicone rubber to 90 parts of polyolefin, then theconcentration of the PTFE in the final composition will be atapproximately 0.5% level.

Accordingly, an operable range of PTFE in a polymer interdispersion willvary from a small fractional percentage to about 35%. Ultra highmolecular weight polyethylene should be employed in higherconcentrations of the order of three or four fold higher than PTFE toachieve the similar effect as an interdispersing agent and the highmolecular weight polyethylene should be employed in still higherconcentrations, approximately 50% higher than the ultra high molecularweight polyethylene interdispersing agent.

The concentration of fibrous PTFE for interdispersing distinct polymerscan be substantially lower for some systems which do have somecompatibility and blendability at a desired set of conditions and canimprove and enhance such blending as taught in Example 26 below.

Another advantage of the fibrous PTFE interdispersing agent of thisinvention is that it is to a large extent non-fusible and compositionscontaining the fibrous PTFE can be heated to relatively hightemperatures, particularly after the fibrous dispersion of PTFE has beenformed without causing degradation of the PTFE.

The use of fibrous PTFE is deemed to vary with the polymerinterdispersion system in which it is used so that an optimumconcentration for one system can be at one concentration, and theoptimum for a different system can be at another concentration. See inthis respect Example 27 below dealing with the different concentrationsof PTFE which are incorporated in different polymers, such as naturalrubber and high density polyethylene, and the startlingly differentconcentration of PTFE which can be absorbed into a 50/50 interdispersionof natural rubber with high density polyethylene.

In the processing of polymers, it is preferred to process at as low atemperature as is consistent with obtaining the results which aredesired. Generally speaking, there is an advantage in processingpolymers at lower temperatures partly because exposure of plastic orpolymer material to higher temperatures can initiate the degradationprocesses to which most polymers are subject and, accordingly, shortentheir useful lives.

Accordingly, there is an advantage in the case, for example, ofpolyvinyl chloride of forming an interdispersion of the polyvinylchloride with a low density polyethylene at a temperature in the rangeof about 280° F. rather than at higher temperatures such as 350°-400° F.at which the polyvinyl chloride is conventionally blended as withchlorinated polyethylene. This interdispersion of the polyethylene withthe polyvinyl chloride is an example which is given below, see Example20 and others, and is illustrative of the examples of the processing ofmaterials at a lower temperature with the aid of one of theinterdispersing agents of this invention, specifically, the fibrouspolytetrafluoroethylene.

For example, in the processing of some polymers at higher temperatures,there is a scission which occurs in the polymer to reduce the molecularweight of the polymer into lower molecular weight molecules. It isknown, however, that the properties of a polymer are related to themolecular weight and that the higher molecular weight materials do havedifferent properties than the lower molecular weight polymers.

Accordingly, by use of the interdispersing agent of the presentinvention as taught in the examples below, the advantage of being ableto process and combine such polymeric materials at lower temperatures ismade available.

It has been demonstrated, for example, that polyvinyl chloride can beinterdispersed in polyethylene with the aid of the interdispersingagents of this invention at a temperature about 100° F. below thetemperature at which the polyvinyl chloride can normally be processed toa blend as with chlorinated polyethylene.

FIBROUS MASTICATION

One question which is raised by the interdispersing of the polyvinylchloride particles into the polyethylene with the aid of Teflon 6 at atemperature of about one hundred degrees below the temperture at whichthe PVC can be blended without Teflon 6, is the question of themechanism by which it happens. How does the small percentage of Teflon 6induce the dramatic change in the processing temperature of the PVCpowder?

While the applicants do not wish to be bound by the accuracy of theexplanation which is given here, the explanation is offered to assist invisualizing by analogy a phenomena which is believed to take placeprogressively in finer and finer degrees of subdivision starting withthe particles of Teflon 6 powder, which are visible in bulk to theunaided eye, and proceeding down in size scale to the fine strings andthreads which are also visible to the unaided eye spanning the folds ornodes in the beads of polymer fluxing in the nip of a small laboratorymill. Careful observation of these strings, which are arrayed inparallel across each node in harp-string formation by means of a lowpower magnifying glass, reveals that they are not single threads, butweb networks of threads in filigree formation likely enmeshing hostpolymer material incorporated and suspended in the webs. U.S. Pat. No.3,005,795 referred to above sets forth the observations that the fibersof the PTFE-A referred to in the patent subdivides progressively fromlarge bundles of fibers to smaller and smaller bundles and into a sizedomain below the resolving power of the optical microscope.

It is the applicants conception and understanding of the morphology ofthe fibrous PTFE that as its fibers are progressively subjected toshearing action of a host polymer, the fibers of the PTFE which areformed under conditions which give them extraordinary length, willcontinue to unravel from their progressively smaller diameter bundlesuntil they have passed through and below the resolving power of thescanning electron microscope and become ultimately single extra-longmolecules.

A molecule of such extraordinary length is uniquely able to interactwith molecules of the host polymer partly because of its unique length.On a statistical basis, an average Teflon 6 molecule is believed to befar longer than an average molecule of almost any host polymer in whichit is likely to unravel to its monomolecular form. The Teflon 6 moleculeis estimated by Fred Billmeyer in his book "Textbook of PolymerScience", 2nd Edition, published in 1962 by John Wiley & Sons of NewYork, to have a molecular weight of many millions.

The fibromorphous transition of PTFE which accompanies shear in polymersor other fluid media can accordingly, by this mechanism, be seen to be away of concentrating a very high degree of energy on a particle capturedin the polymer undergoing fluxing.

Even though PTFE is acknowledged in most references on polymers to bethe most lubricious of all polymer species, and the exhibition of thismacro property may reasonably be thought to emanate from the display ofsimilar property on a micro scale, and even down to the monomolecularscale, it is nevertheless the phenomenal length of the monomolecularfilament and of the filament bundles constructed from suchmacromolecules which are deemed to be the source of an extraordinaryforce concentration.

By this conception, because the PTFE molecule is so phenomenally long,it can entwine with a vast number of individual molecules and moleculebundles along its unique length. When one entwined end of such amolecule is moved in a first direction and the other entwined end ismoved in a different direction, an extraordinarily large masticatingpressure can be exerted at the mid-molecule region even though themolecule itself is quite slippery or lubricious because the force, whilegenerated by the multidirectional movement of masses of polymer, istransmitted and applied as pressure in an ultimate width of only asingle molecular chain. The masticating pressure exertable by a singlemolecule entwined at each end in differentially moving masses of polymeris so extraordinarily high because the area over which the generatedforce is delivered to an embedded particle is so extraordinarily small.

If the PTFE molecule fiber or bundle of molecule fibers bears against aPVC particle embedded in the polyethylene, the result is similar toplacing a fine wire over a block of ice and hanging weights from the twopendant wire ends. The wire will cut through and sever the ice blockwithout melting the whole block and at a temperature below the meltingtemperature of the ice block.

But, if as a result of shearing which accompanies conventionalprocessing of polymer compositions this procedure is repeated over andover again with smaller and smaller blocks, the PVC particle is in thisway masticated and dispersed into the composition by repeatedsubdivision. It is the inventors' concept that the PVC interaction withthe fibers is on a progressively more reduced size scale passing themicroscopic and submicroscopic scales and ultimately approaching amolecular scale. With a sufficient degree of shearing, theinterdispersion of the polymers is deemed to be accomplished on a scaleapproaching a molecular scale. In addition, the fibrous masticatingagent remains in place after the interdispersion is formed and servesalso as an interlocking agent in holding the polymers in theinterdispersed form. This fibrous mastication is deemed to occur for thePTFE interdispersing agent as well as for the high molecular weightpolyethylene and the ultra high molecular weight polyethyleneinterdispersing agents.

Accordingly, pursuant to the present invention, it is preferred toaccomplish the fibrous mastication of PVC by starting with powdered PVCand incorporating and internalizing the PVC particles in a plasticpolymer medium such as polyethylene in which the fibromorphoustransition of an interdispersing agent such as the PTFE can proceed asthe polymer medium is sheared. Shearing separates the fiber bundles intothe phenominally long fibers and imparts the high energy to and alongthe fibers, which energy is delivered to the enmeshed particles to bemasticated.

Accordingly, the PVC is masticated into and interdispersed with thepolyethylene at a temperature about one hundred degrees below itsconventional working and blending temperature. For this reason, informing interdispersions, it is preferred to form an interdispersionwith finer particles of a higher temperature material such as PVC and toembed such finer particles in a plastic medium such as polyethylene inwhich the fibrous network, such as the PTFE network, can subdivide andmasticate the embedded particles.

This same fibrous mastication of higher melting particles does not occurwhen the fibers or filaments and ultimately the molecules of a potentialfibrous interdispersing agent are shorter because the fiber ends do notentwine as strongly in the oppositely moving masses of polymer in theplastic being subjected to macroshearing.

In the practice of this invention, it is preferable for a higher meltingmaterial to be incorporated into a lower melting polymer undergoingshear in the form of powder of such grain size that they can be embeddedin the lower melting polymer. In this regard, it is preferred to havehigher melting materials in powdered or granular form rather than inpellet form and to add the powder to the lower melting material fluxingin the shearing apparatus.

As indicated above, the action of the fibrous interdispersing andinterlocking agent is deemed to be at least part physical and thisconclusion is reached in part because the interdispersing andinterlocking of diverse sets of polymers occurs with the finedistribution of the fibrous material in the polymers and it does soessentially without regard to the chemical nature, or other affinityfactors such as are referred to above, of the polymers which arecombined and interdispersed into an intimate interlocked structure.There may also be present some induced intermolecular attractions orforces, either of the distributed fibrous material with the hostpolymers or between the two or more polymers of the host polymericinterdispersion itself, but the applicants here are not aware of anysuch phenomena which can be described and, accordingly, offer noexplanation or description here.

The applicants are aware that for certain interdispersions which havebeen studied, there are improvements in the properties which areobserved and these are pointed out below in the examples. However, theymake no assessment as to the origin of the improvements other than thatthey are found in compositions in which the finely dispersed fibrousmaterial is also found.

In the examples which follow, a powdery form of PTFE orpolytetrafluoroethylene was employed. The powdered PTFE was thatavailable from Du Pont under the trade designation Teflon 6 and ispreferred in the practice of the present invention.

It is known that one of the more severe tests of a composition which hasbeen apparently blended, but which may be only partially blended orpoorly blended or which may not be a stable and persistant blend, is thetest of subjecting the composition to the high levels of shear which areinvolved in injection molding. If the composition survives withoutsegregation the high shear which is incidental to injection molding,then it is likely also to survive other processing such as milling,extruding, high intensity mixing and the like, which involve lowerdegrees of shear without segregation of the polymer components and othercomponents of an apparent blend composition.

As described below in Example 1, a composition having an interdispersedset of polymers as a base was prepared first by high intensity mixing inbatch form and then by extruding the composition as a wire insulationonto a conductor to form a cable product. The composition was preparedfirst as a composition containing no crosslinking agent at a highertemperature and then prepared to include the crosslinking agent at alower temperature as part of the conventional wire insulation formingprocess of Example 1.

As a separate test of the tendency of the composition of Example 1 toremain interdispersed and to have the normally incompatible ingredientsstay together during processing, the interdispersed uncrosslinkedcomposition containing no peroxide crosslinking agent was subjected toan injection molding test to form an injection molded part about threesquare inches in size. This injection molding was carried out in aStokes Machine Model 702-1 manufactured by F. J. Stokes Corporation ofPhiladelphia, Pa. For this particular run made with an interdispersedcomposition of Example 1 without any peroxide present, the machinebarrel temperature was 400° F.; the mold temperature was 150° F.; themold filling time was 5 seconds and part cooling time before ejectionwas 50 seconds. It was observed, as pointed out below in Example 1, thatthe composition did retain its homogeneous composition after injectionmolding and that the normally incompatible ingredients, namely highdensity polyethylene and ethylene propylene rubber, did remainintimately interdispersed in the injection molded product and were notsegregated or laminated (sometimes referred to as "delaminated") as aresult of the injection molding.

The preparation of the composition of Example 1 without a crosslinkingagent was carried out with very extensive care to carefullyinterdisperse the ingredients.

Another injection molding test was done on two interdispersedcompositions which were not at all optimized as to the degree ofinterdispersion before being subjected to the injection molding test.

The first composition was prepared with 20 parts of polystyrene, 80parts of low density polyethylene and 1.8 parts of fibrouspolytetrafluoroethylene. It was milled on a large mill to give aquantity sufficient to form several injection mold samples. The milledcomposition was removed from the rolls in sheet form and cooled.

When cooled, the composition was fairly smooth-surfaced and was removedfrom the roll with relative ease and with a minor tendency to stick tothe roll. The total milling time was about 20 minutes. No attempt wasmade to optimize the degree of interdispersion by time, temperature,degree of PTFE dispersion, concentration of PTFE, secondary treatments,additives of any type other than the conventional antioxidant or by anyother procedure, manner or means.

The cooled sheet resisted fracture with hand force and a white areadeveloped in an area of the surface before a crack appeared in the area,possibly suggesting fibrous architecture. After the sheeted product wasbroken with hand force, it exhibited a high degree of fibrous structureat the break. The fracture surface showed laminar or layer-likestructure.

The sheeted material was granulated in a conventional granulatingmachine. The granulated composition was introduced into an injectionmolding machine and injection molded to form a part corresponding to theinjection molded part of Example 1.

The product formed had a smooth shiny surface and conformed well to theshape of the mold.

The product formed broke with roughly the same degree of hand force asthe sheet material. The type of lamina found in the broken edge of thesheet material prior to injection molding were also observed in thebroken edge of the injection molded material. Both the milled sheetmaterial and the injection molded material were quite tough in theirresistance to fracture and in the evidence of fibrous content andcharacter of the material exposed at a broken edge. In fact, the sheethad a tendency to undergo considerable folding before a break occurred.

The evidence that fibers were present was very clear, but is was notdetermined whether these fibers were solely PTFE or were PTFE associatedwith the host polymer material. The strong evidence of fibers and theknown tendency of PTFE to fillibrate under shear in a polymer mediumstrongly suggested at least some PTFE fiber presence.

This demonstration is deemed to evidence that polytetrafluoroethylenefibers and fiber bundles can go through the high shear of injectionmolding. It is also possible that the fillibration of the PTFE isenhanced by the high shear which accompanies the injection moldinginasmuch as the fillibration is generally enhanced by shear in the hostpolymer.

Accordingly, the present invention provides injection molded articleswhich have fibrous polytetrafluoroethylene distributed therein.

Another interdispersion of low density polyethylene and polystyrene,specifically one prepared in the lower end of the temperature range forforming such interdispersions using 1.8 parts of PTFE, was made to have20 parts of low density polyethylene in 80 parts of polystyrene. Also,this 20 polyethylene/80 polystyrene interdispersion was repeated using 5parts of PTFE.

These compositions were also prepared for the first time in largerquantity on a larger plastic mill. They were also taken off the mill insheet form and showed evidence of lamina at the surfaces formed as thesheet was broken.

The sheets were granulated and each granulated composition introducedinto an injection molding apparatus. The injection molded productsformed each had a smooth shiny surface closely conforming to the moldshape.

Breaking of the injection molded pieces revealed lamina similar to thoseof the unmolded sheet material and also strong evidence that the fibrousform of the composition had survived the high shear of the injectionmolding to form the molded product. The material representing 5 partsPTFE was much more resistant to breakage in both the unmolded mill sheetand the injection molded part.

Where the PTFE is initially well distributed in a wholly homogenizedinterdispersion such as that produced according to Example 1, theapplicants have found that for such a wholly homogenized interdispersionprovided pursuant to this invention, the injection molding of arelatively small part of the order of a few square inches in size doesnot result in such a disruption of the homogeneous interdispersion orsegregation of the normally incompatible ingredients of theinterdispersion so as to cause observable lamina to form in theinjection molded part.

None of the samples involved in these injection molding experiments hadbeen subjected to any secondary processing.

It is contemplated that interdispersion compositions prepared forinjection molding should preferably have a degree of dispersion of thefibrous PTFE which is slightly less than optimum so that the additionaldispersion of the fibrous PTFE which occurs during the very intenseshear of injection molding will bring the dispersion of the fibrous PTFEto an optimum level.

It is known that some natural blends based on natural compatibility andalloying of ingredients do form laminar products when subjected toinjection molding in the formation of larger parts of more complexshape. However, it is within the scope of this invention to includesmall amounts of fibrous PTFE in such naturally compatible compositionsto aid and assist in the injection molding of such materials to formlarger and more complex parts and to reduce the degree of lamination ordelamination which can result from such injection molding of largerparts of complex shape.

It is known that the incorporation of certain flame retardants inpolymer materials improves the flame retardance. Materials which needsuch flame retardant additives are those which are themselves less flameretardant. For example, it is known that polyvinylchloride has arelatively high degree of flame retardance due principally to thepresence of the chlorine component of the monomer and of the polymerformed from the monomer. Pursuant to the present invention, it isfeasible to disperse a material such as polyvinylchloride into otherpolymer materials which do not contain PVC. As for example by Example39, it is demonstrated that an interdispersion of PVC can be made with apolyolefin such as high density polyethylene, and by another Example33B, 80 parts of linear low density polyethylene were interdispersedwith PVC. Also by Example 43E, PVC can be interdispersed withpolystyrene to make an easily handleable composition. In general, it isfeasilbe pursuant to the present invention to interdisperse chlorinecontaining polymeric materials such as PVC with other polymers in orderto improve flame retardance through such interdispersing.

With further reference to the primary treatment and primary formation ofan interdispersion of diverse polymers, it will be understood thatunique and valuable properties are imparted to such primaryinterdispersions and that it is not necessary to apply a secondarytreatment or processing, such as crosslinking, to a primaryinterdispersion, in order to achieve a composition having unique andvaluable properties and uses.

In this connection, the above illustration regarding PVC andpolyethylene is pertinent. For example, it has been found that a 50/50mixture of low density polyethylene and PVC (also contained 1.5 parts ofFlectol H and 10 parts of dibasic lead phthalate) when formed ihto amixture without one of the interdispersing agents of the presentinvention and than formed into a rod about 40 millimeters long, 1.5millimeters wide and 1.5 millimeters thick, will, after being ignited,burn continuously in the vertical position with the flame at the upperend.

A second sample of essentially the same dimensions was prepared inessentially the same way with the same ingredients in the same ratios,but with the exception that it contained 1.8 parts of PTFE andconstituting an article formed from an interdispersion of the PVC andlow density polyethylene. This sample self-extinguished after ignitionwhen held vertically with the burning end up.

As is well known, for example, that thermoplastic low densitypolyethylene is not flame resistant and that a rod of the polyethyleneburns like a candle when ignited and held in a vertical position withthe flame up. By contrast, thermoplastic polyvinyl chloride is known tobe flame resistant and that it will not support combustion when held ina vertical position with the flame up. In fact, PVC will not burn afterapplication of flame to ignite it when held in a horizontal position oreven in an inverted position.

Accordingly, pursuant to this invention and with the aid of theintrdispersing agents of this invention, it is feasible to combinedistinct polymer materials into a combined form, herein referred to asan interdispersion, which interdispersion exhibits properties which arenot exhibited by the individual polymer ingredients of the combinationand also which are distinct from the properties exhibited by a mixtureformed by processing the same polymer ingredients in essentially thesame proportions in the same apparatus and under the same conditions.

Many compositions having a polymer base, where the polymer base may behomopolymers, copolymers or combinations of different polymers,including both combinations of homopolymers and combinations ofhomopolymers with copolymers in different proportions, when heated willprogressively soften and as they soften will eventually reach a liquidor liquid-like highly plastic state. One common problem in trying tocombine polymeric materials is that the liquid state of one prospectivepolymer component of the combination is reached at a lower temperaturethan that of the other component or components. Preferably, materialswhich can and do combine well together naturally not only have somegeneral molecular structural affinity, but they have a range of plasticproperties which extend over a temperature range having some commontemperature for the different species. Accordingly, if a materialbecomes plastic at 100° and a second material also has plasticproperties at or near 100°, there is a much better chance of blendingthem together than if there is one of the materials in a plastic stateand the other in an essentially liquid state.

Uniquely, surprisingly and unexpectedly, the compositions of the presentinvention can be employed to form an interdispersion of polymers whichhave different ranges of temperatures at which the materials exhibitplastic or plastic-like properties.

According to one concept of the present invention, the range in whichthe material can be deformed and processed and interdispersed under highshear mechanisms, is due to the presence of an extremely high molecularweight polymer, essentially linear, which in the case of Teflon 6,concommitantly manifests macroscopic and microscopic fibrosity, andwhich material uniquely disperses in the medium of the plastic hostmaterial to exhibit pseudo liquid or pseudo plastic properties and toexhibit these properties through a very broad temperature range up tothe temperature at which the unique material itself undergoesdecomposition.

It is recognized by the applicants hereof that although the PTFEmaterial which is responsible for the modification of many properties ofthe polymers to which it is added that the PTFE itself is not subject tothermal fusion and is not subject to thermal bonding. The behavior ofthe fluorocarbon by itself is well known and has been studied and hasbeen published by the inventors and manufacturers thereof in numerouspatents and publications.

However, the properties of the PTFE homopolymer powder by itself aredistinct from the properties which this material exhibits when it isfinely dispersed and distributed through an interdispersion of hostpolymer materials, particularly, where the host polymer materials are atelevated temperatures and at temperatures at which one of the polymersmight normally be in a liquid state.

One of the key points in the operablility of this invention employingPTFE at higher temperatures is the non-fusability in the plastic polymermedia of the fibrous PTFE on which the process apparently depends. Thismaterial, that is, the fibrous PTFE, can induce an interdispersedpolymer material in which it is dispersed to continue to exhibit aplastic behavior at temperatures at which such plastic behavior mightnot otherwise be exhibited.

POLYMER ADDITIVES

There are a number of compositions which are polymer materials, whichmaterials may give beneficial properties to other polymer base materialsalthough present only to a relatively low concentrations as a polymeradditive to the base material.

Pursuant to the present invention, concentrates of such polymericadditives are prepared by incorporating relatively high percentages ofthe PTFE at least partially in fibrous form in the additive to beblended into the base polymer to achieve a relatively low concentrationof the additive in the base polymer. By relatively low concentration asused herein is meant a concentration of less than 10%.

Additives may be included in base polymers to possibly improve a numberof different properties. For example, a basis host material may besubject to stress cracking and a relatively low level polymer additivemay possibly improve the stress cracking of the basis host material.Similarly, improvement in a property such as impact resistance maypossibly be achievable by inclusion of a polymer additive.

Alternatively, a base polymer may be subject to degradation due tosunlight and a polymeric additive may possibly impart properties,although present in relatively low percentages, which increase theresistance of the basis host polymer to such light degradation orphotodegradation.

Alternatively, a material may be subject to degradation due to oxidativeattack. The addition of the stabilizing additive polymer in a smallpercentage may possibly improve resistance of a basis host polymer tosuch oxidative attack.

Similarly, resistance of polymer materials to other deficiencies canimprove by the addition of certain low concentrations of additivepolymer materials, either low molecular weight or high molecularadditive materials, to base polymers to overcome the deficiency ordefect of the base material.

The use of polymeric materials in low concentrations as additivematerials to alter a certain aspect of the properties exhibited by hostpolymers has been limited heretofore because of the incompatibility ofmany such potential polymer additives in distinct base polymers.

However, the present invention is deemed to make possible numerousadditional combinations of polymeric additives into base polymers asinterdispersions of the base and additive polymers to enhance propertiesof the base polymer.

The present invention has been demonstrated to operate in regard to theinterdispersing under a given set of conditions with the aid of aninterdispersing agent of an experimental number of sets of polymerswhich it was found could not be interdispersed under the same set ofconditions in the absence of the polytetrafluoroethylene interdispersingand interlocking agent. The PTFE interdispersing of this experimentalnumber of sets of polymers is set forth in the examples below. There isevery reason to believe that there are numerous additional multinarysets of polymers which cannot be interdispersed in the absence of thefibrous interdispersing agents of this invention or which can only bepartially or poorly interdispersed in the absence of suchinterdispersing agents but which can be interdispersed by this inventionto form interdispersions of distinct polymers of a desired degree ofinterdispersion or, in other words, a desired degree of intimacy ofcontact which may approach the molecular level.

Among the polymers which can be interdispersed in each other inmultinary combinations and which are deemed to be useful in forminguseful insulating compositions are the following:

    ______________________________________                                        Low density polyethylene                                                                         Polyphenylene oxides                                       Linear low density polyethylene                                                                  Ethylene ethyl acrylate                                    High density polyethylene                                                                        rubbers                                                    Low molecular weight poly-                                                                       Fluorocarbons                                              ethylene                                                                      Ethylene propylene rubbers                                                                       Silicone polymers, including                               Polyvinyl chloride silicone gums and silicone                                 Ethylene vinyl acetate copolymers                                                                fluids                                                     Styrene butadiene rubber                                                                         Polystyrenes                                               Thermoplastic elastomers                                                                         Sioplas polymers                                           Chlorinated polyethylene                                                                         Natural rubber                                             Polypropylene      Chloroprene                                                Polyetherimide     Polycarbonate                                              Polyesters         Polymethylmethacrylate                                     Polyamides         Polyacetal                                                 ______________________________________                                    

By incompatible polymers as used herein is meant polymers which, under agiven set of conditions such as are attainable in conventional polymerprocessing equipment, do not enter an intimate blend although there maybe other conditions usually involving higher energy input at which theymay be apparently blended and to some degree which conditions may, forsome polymer systems, be attainable in the same conventional polymerprocessing equipment.

While the invention has been described principally with reference to theimprovement in the interdispersing to a desired degree of intimacy ofcontact of poorly compatible materials and also the interdispersing ofincompatible materials or of materials which are incompatible under theset of conditions at which blending is attempted, the teaching of thisinvention extends to the improvement in the combined properties ofmaterials which are blendable or which are naturally compatible. Forexample, styrene and polyethylene, when heated to a sufficiently hightemperature and mixed together, form what is to the unaided eye anapparent blend of the two materials. For example, as is pointed out inExample 30 below, where 50 parts of polystyrene are milled at 310° F.with 50 parts of low density polyethylene, a composition is formed whichhas the appearance of a blend.

However, the same two ingredients when milled in the same proportions atabout 240° roll temperature, does not blend at all, even apparently, butforms flakes of polyethylene and dispersed particles of polystyrene inthe polyethylene. However, the formation of an interdispersion of thesame ingredients in the same proportions can be effected by means of thepresent invention at the much lower temperature of 240°-250° F. and canfurther be improved by the addition of the fibrouspolytetrafluoroethylene interdispersing agent as part of theinterdispersing process.

Based on the examples given below, such as Examples 30 and 31, thepresent invention extends to the improvement in the combining of thematerials into an interdispersion and in the interdispersion propertiesof the combined materials which, under the higher temperature or otherspecial conditions, can be made to enter what appears to be a blendedcondition by accomplishing the combining at a lower temperature with allof the advantages which attend the lower temperature combination, someof which are known in the art and others of which are pointed outherein.

"PTFE interdispersable" as used herein means that the distribution offibrous PTFE in a set of polymeric materials permits the binding of thepolymers into an intimate interlocked interdispersion and/or thepreservation of such interdispersion under conditions under which ablend or apparent blend would not otherwise form or to persist underconditions under which it would not otherwise persist.

In general, the PTFE interdispersing is achieved with a lower level oftemperature and other energy input to form the intimate interlockedinterdispersion or to preserve the intimate interlocked interdispersionthan is otherwise feasible.

With regard to the lower energy of interdispersion formation, anillustrative case is the case of the formation of a binaryinterdispersion of polyethylene and polystyrene in a 50/50 ratio. Aninterlocked blend of these two materials can be formed with the aid offibrous PTFE at a mill roll temperature of 240° F. because thecomposition is PTFE interdispersable at the 240° F. If the binaryLDPE/PS composition is milled at 240° F. without the PTFE, no blendforms between the low density polyethylene and the polystyrene and themilling can be continued for a very extended period without achievingblending as taught in Example 31 below. Also, as an alternative, the50/50 LDPE/PS composition can be raised to 310° F. and apparentlyblended on rolls operating at this temperature and, accordingly, at ahigher energy consumption as described in Example 30 below. However, thesame 50/50 blend of LDPE/PS can be interdispersed with lower energy bymilling at about 240° F. and adding a small amount of PTFE as taught inExample 31 below.

In the above described examples, the difference in milling temperaturesand the ability to form an intimate interlocked interdispersion at thelower temperature can be significant not only because the polymer systemhas "seen" or been through an overall lower temperature profile sincethe inception of the polymer ingredients of the interdispersion, butalso because it makes possible a different array of secondary processingsteps.

For example, a reasonably priced and very widely used peroxidecrosslinking agent is dicumyl peroxide. This material is usedextensively and its use is described illustratively in the examplesbelow. Its commercial identity and source are set forth as in Example 1.

The dicumyl peroxide crosslinking agent can be milled into a compositionundergoing milling at 240° F. without initiating thermal decompositionof the peroxide. If a small amount of dicumyl peroxide as, for example,0.1 parts, is milled into a composition which is milled to intimateinterlocked interdispersion with the aid of the fibrous PTFE, then thecomposition will become essentially homogeneous with regard to thedistribution of PTFE, the two polymer ingredients of theinterdispersion, and the peroxide crosslinking agent before anydecomposition of the peroxide agent and before any crosslinking occurs.

By gradually raising the temperature of the composition while it isundergoing milling or high intensity mixing, a partial peroxidecrosslinking can be induced between the polymeric constituents of theinterdispersion while they are in the intimately admixed status of theinterdispersion. Such a lower temperature interdispersing of allconstituents and partial peroxide crosslinking of some of theinterdispersed polymers is not feasible for an apparent blend formedaccording to Example 30 because the temperature of blending of 310° F.necessary to form the blend is above the decomposition temperature ofthe peroxide crosslinking agent and the peroxide as well as the polymermay accordingly not become uniformly distributed before decompositionoccurs. Accordingly, where a thermally decomposable secondary processingagent such as dicumyl peroxide is added to a composition to be blendedat a temperature above that at which decomposition occurs, the polymeringredients do not have a chance to combine to best advantage before thethermal decomposition and secondary process is initiated. In otherwords, the secondary processing occurs in such case before the primaryprocessing is complete or brought to a desired stage of completion.

This is another indication of the advantage of the invention whichrelates to the lower energy level at which polymers can beinterdispersed with the aid of fibrous PTFE pursuant to this inventionand of the opportunity made possible by such lower energyinterdispersing of imparting secondary processing treatment steps to theinterdispersed composition because of the lower energy interdispersingmade possible by the present invention.

Another illustration of this phenomena is the addition of benzoylperoxide to a low density polyethylene-containing interdispersion atabout 170° F. This temperature is well below the conventional processingtemperature for low density polyethylene-containing mixtures.

In preparing the interdispersed compositions of the present invention,it is sometimes advantageous to have the PTFE well dispersed in a firstpolymer before the second polymer is added. The level of concentrationat which the PTFE affects the properties of the first polymer andpermits the interdispersion of a second distinct polymer is quite low.

With less than one-tenth of a part addition, there is a very noticeablechange in the extensability or stretchability in low densitypolyethylene material, in the strength of the material, and in thereduction of the degree of adherence to the mill so that it releaseseasier from the mill. It is believed that effective interdispersing of asmall amount of a second and distinct polymer will occur at and belowthis level of concentration of PTFE. From the changes which occurred itappears to us that it may be possible to add as little as perhaps 5/100of one part to cause a substantial change in the properties exhibited bya homopolymer, such as polyethylene, and which will permit theinterdispersion of small amounts of a second polymer into the firstpolymer bearing the PTFE as, for example, into low density polyethylene.Accordingly, it appears that the interdispersion effects at low level ofsecond polymers obtainable through the present invention may beobtainable at levels of powdered PTFE or the order of 5/100 of one part.The phenomena may occur perhaps as low as 1/1000 of a part. The use ofsuch low levels of PTFE in forming partial interdispersions ofcompatible polymers and to improve interdispersion as well as propertiesof poorly compatible as well as of in compatible polymers iscontemplated as within the scope of the present invention.

MOLECULAR WEIGHTS

The present invention is adapted to the multinary interdispersing ofdistinct polymers with the aid of fibrous PTFE. The polymers may beorganic or inorganic and the interdispersions formed may beinterdispersions of organic polymers with other organic polymers, theymay be inorganic polymers with other inorganic polymers, or they may beinterdispersions of organic polymers with inorganic polymers.

From the great diversity of polymers which have been interdispersed withthe aid of fibrous PTFE, it is evident that a wide variety of polymericmaterials are interdispersable with the aid of the fibrous PTFE or itsequivalent fibrous agent, such as ultrahigh density polyethylene, asdiscussed above.

The term polymer connotes generally, and by conventional usage, arelatively larger molecule polymer as distinct from dienes, trimers andthe other relatively lower level polymer molecules.

Technically, a polymer may include simply a dimer, that is, a polymersuch as polyethylene in which the structural formula may be representedas follows: ##STR1## in which the "n" is 2.

Allowing for end capping, an ethylene dimer is a very small molecule andis simply butane, or structurally, it is: ##STR2##

Polyethylene in which "n" is 3 is a trimer of ethylene is also a verysmall molecule and is simply hexane, or structurally, it is: ##STR3##

The scope of the present invention does not extend to theinterdispersing of dimers or trimers and other very small molecules witheach other.

However, it does extend to the interdispersing of one polymer intoanother where one polymer is a relatively low molecular weight polymerand the polymer into which it is blended is a higher molecular weightpolymer. For example, low molecular weight silicone fluid has beenblended into low density polyethylene.

This low molecular weight silicone fluid having a viscosity of 30,000centistokes was incorporated successfully into the low densitypolyethylene with the aid of fibrous PTFE although an attempt toincorporate the same material into low density polyethylene by fluxingon a polymer mill under the same conditions was entirely unsuccessfulwhen the fibrous PTFE was omitted.

The incorporation of low molecular weight polymer in higher molecularweight polymer with the aid of fibrous PTFE is within the scope of thepresent invention.

Further, it was possible experimentally to at least tentativelyincorporate about three parts of a liquid silicone having a viscosity of10 centistokes in low molecular weight polyethylene by the use of thefibrous PTFE although the liquid could not be incorporated in the lowdensity polyethylene at all without the aid of the fibrous PTFE.

This processing of low molecular weight polymer is discussed in Example36 below.

As a lower limit, the molecular weight of polymers which arebeneficially interdispersable and otherwise processable with the aid offibrous interdispersing agents of this invention is deemed by theapplicants herein to be of the order of 600 to 1000.

As used herein, the term copolymer includes terpolymers and otherpolymers made with more than two monomers.

The term ethylene propylene copolymer or ethylene propylene rubber isintended to include the copolymer made with only ethylene and propylenemonomers, as well as copolymers made with ethylene, propylene and dienemonomers.

CONCENTRATES

The concentrates are compositions in which the percentage of fibrouspolytetrafluoroethylene dispersed in a polymeric medium is relativelyhigh.

The concentrates are not materials which are necessarily intended forend use application themselves, but rather may be compositions whichcontain higher levels of the fibrous PTFE and which permit thedispersion of the PTFE in fibrous form into polymeric medium withrelative ease of processing.

For example, it has been found possible by milling on a small rubbermill as described in the examples below, to introduce approximately 6parts of the fibrous PTFE into natural rubber before the compositionbecomes poorly millable.

It was also found experimentally that it was possible to introduceapproximately 12 parts of the fibrous PTFE into high densitypolyethylene on the mill before the composition became poorly millable.

However, it was found that when the fibrous PTFE was introduced into a50:50 interdispersion of high density polyethylene and natural rubber,that approximately 25 parts of the fibrous PTFE could be incorporatedinto the interdispersion before the composition became poorly millableto a degree similar to the degree reached with the natural rubber aloneand with the high density polyethylene alone.

Accordingly, pursuant to the present invention, concentrates of PTFE invarious polymer media can be prepared and the concentration of the PTFEin the polymer media will depend on the concentration of PTFE which isneeded for a particular application and also on the different levels anddegrees of the dispersability of the PTFE in the polymeric materials.

THERMAL HISTORY

It is well accepted in the plastics industry that there is an advantagein the processing of polymeric materials through a thermal history whichmay be referred to for convenience of reference as one having a "lowprofile". What is meant is that if the polymer from the time of itsinception in the polymeric state is exposed to and subjected to athermal history, which is of a low profile type rather than a highprofile type (i.e., with temperature plotted as ordinate and time asabcissa), that the polymer will have a better chance of retaining itsproperties and a better chance of avoiding the initiation of thedegradative processes to which essentially all polymeric materials aresubject. In general terms, the performance of a polymeric product may beinferred to be reciprocably related to the cumulative excessive thermalhistory that the material has experienced.

Contrasted with this preferable low profile history is the recognitionthat if a polymeric material is taken to a sufficiently hightemperature, it may be made to undergo unique transformations orreactions. For numerous polymer systems, one such unique transformationis an intermingling and blending of two or more polymers of such asystem which can not be achieved at lower temperatures.

Accordingly, it is possible in varying degrees for different polymericmaterials to accomplish an apparent blending of the materials if thematerials are taken to a sufficiently high temperature and subjected toa sufficiently high level of intermixing or shearing. Such apparentblends may be persistant when cooled or they may segregate. They alsomay delaminate when injection molded. There are not many such apparentblends which have achieved appreciable commercial or industrial use.

One element of blending is a high degree of intermingling. This can beaccomplished in part by increased mechanical agitation and in part byincreased thermal exposure to two candidate polymer materials of asystem as they are subjected to intense agitation and mixing. Thepolymers of such system may be closely intermingled because theincreased temperature increases the tendency of the materials tointermingle on a molecular basis.

Accordingly, considering the subject application and the invention inthe context of the ability to subject materials to extremes oftemperature and agitation, it will be recognized that one of theprinciple advantages of the present invention is the achievement of theinterdispersing at what is deemed to be essentially the molecular levelwithout subjecting the materials to such extremes of temperture oragitation or intermixing.

Accordingly, one advantage made possible by the present invention is thereduction in the overall thermal history of materials which areintimately interdispersed. As used herein, the term thermal history isintended to include the temperature to which a polymer material israised; the cumulative times which it is at such raised temperatures;the other energy which is put into such material; the level or degree ofother energy inputs are made; and the cumulative time during which suchinputs ar such levels are made.

Although in this context of using extremes of temperature and agitationnumerous polymer materials can apparently be blended with other polymermaterials, to the applicants' knowledge no effort has been made todevelop and use significant numbers of such apparent blendscommercially. This appears to be principally because the properties ofthe materials are found to be inferior in some respects.

For example, the apparent blend produced according to Example 4 wasfound to be deficient in tensile properties and in the roughness of itssurface properties for the intended use as a cable insulation material.

As another illustration, in Example 24 below, a composition 24Acontaining an apparent blend of linear low density polyethylene and EPDMwas made under a given set of processing conditions without any Teflon6. Its tensile and elongation properties were tested.

Teflon 6 was then added to the same composition under the same given setof processing conditions to form an interdispersion sample 24B and itstensile and elongation properties were also measured.

The test results are as follows:

    ______________________________________                                                   SAMPLE 24A                                                                              SAMPLE 24B                                               ______________________________________                                        Tensile in psi                                                                             1453        2483                                                 Elongation in %                                                                             426         550                                                 ______________________________________                                    

The significantly lower tensile and elongation values obtained forsample 24A as compared to sample 24B are deemed to evidence that theseproperties of apparent blend are deficient relative to the PTFEcontaining blend.

Applicants believe that, in general, the properties of apparent blendsprepared under the same processing and treatment conditions asinterdispersions prepared with the aid of the interdispersing agents ofthis invention are deficient in some properties.

As used herein, the term "systems" connotes a combination of a firstpolymer with at least a second polymer in which the proportions of thefirst and second polymers are varied over a wide range, and in whichdifferent sets of properties are evinced by the combination of polymersin the different proportions including different proportions of thepolytetrafluoroethylene interdispersing agent of this invention.

By "physical interdispersing" is meant herein, interdispersing with theaid of inducing motion in the composition as by stirring or otheragitation and, particularly, the agitation which induces a high level ofshear in the composition and can include heating by whatever meansincluding imparting heat to the composition by the agitation itself as,for example, by a work heat or the like. But such physicalinterdispersing does not include chemical interraction, such as arenecessary to form chemically linked polymers in the form of copolymers.

One of the characteristics of the combination of fluorocarbons with thepolymer base medium which is significant in achieving the results of thepresent invention, is the ability of the fluorocarbon to form intofibers which become associated with the host polymer and becomedistributed in the polymer. It is not understood why the fluorocarbondevelops the fibrous form which it does, nor is it understood why thehost polymer associates with these fibers and undergoes a significantchange in its properties, but it is found that when the fluorocarbondoes form the elongated fibers or filaments and does become distributedin the host polymer and associate with the polymer, that significantchanges occur which permit the interdispersing of polymeric materialswhich are not otherwise blendable by the same physical and thermal meansand methods. Similar modification of host polymer properties andmanifestations are attainable by the distribution of ultrahigh molecularweight polyethylene and of high molecular weight polyethylene in apolymer or a polymer system.

By "high shear" as used herein, is meant a degree of shear which issufficient to cause a filamentary dispersion of polytetrafluorethyleneto form from a powder form of the polytetrafluorethylene present in thematerial being subjected to the shear.

By "filamentary form" as used herein is meant that thepolytetrafluroethylene is strung out into very fine diameter and longstrands or fibers in which the length to diameter ratio is high as it isfor most fibrous strands or filamentary materials.

As used herein, the term "incompatible" means that the polymer speciesdo not blend in one another in significant proportions although theremay be some low level of tolerance of one material in the other whichmay be in the order of a fraction of a percent, a few percent, or up toabout 10 percent. For example, 2,6-poly dimethylphenylene oxide is notcompatible with low density polyethylene although the polyphenyleneoxide does accept a small amount of polyethylene as described in theU.S. Pat. No. 3,361,851. Where the polyethylene is present, it isdescribed in that patent as a plasticizer for the polyphenylene oxide.

Generally speaking, the plastic stage as used herein means that thematerial is not liquid and is not readily flowable and does not easilyand quickly take the form of a vessal in which it is contained, and alsomeans that it is subject to being extensively formed or deformed withoutbreakage. For example, if a plastic material at its plastic stage is ina mechanical agitator and force is applied to the plastic material, itwill deform and repeatedly deform and will be sheared in the process ofbeing deformed, but will not rip or tear or break in this process. Thisplastic stage is the stage in which most blending of ingredients into apolymer material or most interdispersing of polymer materials into eachother is carried out. Interdispersing of a liquid phase polymer into aplastic material is feasible pursuant to the present invention as ispointed out above.

"Creep" is defined as non-recoverable deformation, with time, under aconstant load.

According to the Van Nostrand Reinhold Condensed Chemical Dictionary,the term "engineering plastics" are types to which metal engineeringequations can be applied and are plastics that are hard and stableenough to be treated as a metal. Such materials are capable ofsustaining high loads and stresses and are machinable and dimensionallystable. They are used in construction, as machine parts, automobilecomponents, telephone headsets, and numerous other items. Among the moreimportant are nylon, acetals, polycarbonates and ABS resins, PPO/styreneand polybutadiene terephthalate.

Pursuant to the present invention, interdispersions of engineeringplatics can be and have been made. For example, nylon has beensuccessfully interdispersed with polystyrene and acetal resin has beensuccessfully interdispersed with polystyrene as pointed out in theexamples below. The interdispersing of engineering plastics withnon-engineering plastics and the interdispersing of engineering plasticswith each other is contemplated as within the scope of the presentinvention.

EXAMPLE 1

A novel cable insulation composition was prepared and a cable and aninjection molded part were prepared according to the following example.

In all of the examples below, the term "parts" is used to designate aquantity of an ingredient by weight based on the weight of the polymerbase ingredient of the composition taken as 100. As an example, if thecomposition contains 500 grams of base polymer and 50 grams of anadditive, the content of the composition is stated as 100 parts ofpolymer and 50 parts of additive.

Where the polymer base itself contains more than one polymer, the partsof each polymer ingredient of the base is recited in parts in theproportions they are present in a composition. For example, in thisExample, high density polyethylene is present to a 20% percentage leveland ethylene propylene diene monomer, EPDM, is present at an 80%percentage level. This is recited as 20 parts of high densitypolyethylene and 80 parts of EPDM. Accordingly, in the aboveillustration, if the 500 grams of polymer were 100 grams of high densitypolyethylene and 400 grams of EPDM, the composition would have a polymerbase of 20 parts HDPE and 80 parts EPDM. If the additive were 500 gramsof clay particles, the additive would be reported in the examples belowas 5 parts of clay particles.

Also, if the composition were made up of 400 pounds of EPDM, 100 poundsof HDPE and 50 pounds of clay particles, it would be reported as 20parts of HDPE, 80 parts of EPDM and 5 parts of clay particles.

Accordingly, all quantities of ingredients recited in the examples belowin parts may be readily converted to grams or other weight units. Infact, most examples were made on a small laboratory plastic mill and theparts were directly determined from an equivalent number of gramsactually weighed out.

A set of ingredients and proportions of the ingredients are thoroughlymixed in a high intensity mixing apparatus, such as a Banbury mixer.

The ingredients are introduced into the high intensity mixer which is inmotion and which has an initial temperature of about 150° F. The mixingaction of the high intensity mixer generates heat in the composition andthe composition temperature is measured during the mixing by athermocouple sensor which is built into the high intensity mixer so thata record of the temperature of the sensor can be observed and recordedas on a chart.

When the chart temperature of the composition reaches about 320° F., thecomposition is dropped from the high intensity mixer through a mechanismbuilt into and normally used for this purpose. The heat which thecomposition has received during this temperature rise is a heat ofmixing and no high temperature external heat need be applied in order toattain this temperature increase.

The dropped batch of material, which has a probe temperature (measuredby an inserted thermocouple) of about 340°-360° F., is then milled on aplastic mill after removal from the high intensity mixer. The materialon the plastic mill is banded on the mill and then taken off as sheets.The sheet product is allowed to cool to lower its general temperatureand also the high intensity mixing apparatus is allowed to cool. Thesheet material is reintroduced into the high intensity mixer when themixer temperature is about 150° F. in order that a peroxide crosslinkingagent may be dispersed into the composition of the sheet material at atemperature lower than the drop temperature of the previouslyinterdispersed material as removed from the high intensity mixer. Thedispersing of the crosslinking agent, specifically, a peroxide, is at alower temperature, below the decomposition temperature of the peroxidecrosslinking agent in order to forestall premature crosslinking of theinterdispersion of ingredients. The composition with all of theingredients is mixed in the high intensity mixer at a temperature ofapproximately 250°-270° F. maximum until an apparently homogeneouscomposition is formed.

One unique property of the interdispersed composition, as it is droppedfrom the high intensity mixer, is its very homogeneous, smooth surface.The composition is observed to have no apparent inclusions ofnon-homogeneous structure and, in this sense, the composition is quitenovel and unique, particularly inasmuch as there is no compatibilitynormally of the high density, highly crystalline polyethylene and thesemi-crystalline ethylene-propylene rubber. Quite unexpectedly andsurprisingly, it has been discovered that it is possible tointerdisperse together into a homogeneous interdispersion the twoincompatible base polymers, namely high density polyethylene andsemi-crystalline ethylene-propylene copolymer, and to do so without anyevidence of segregation, delamination, or insufficient mixing, nor ofthe basic incompatibilities of the base polymer materials, namely highdensity polyethylene and semi-crystalline ethylene-propylene rubber. Ithas been known for many years that by their nature, these materials areincompatible and cannot be mixed to form a homogeneous blend. It hasaccordingly been discovered that the fibrous fluorocarbon component ofthe composition is responsible for making it possible to interdispersethe otherwise unblendable high density polyethylene and theethylene-propylene rubber.

Following the introduction of the peroxide crosslinking agent into thepreviously interdispersed compound, it is again rolled on a plastic millinto sheet form from which it can be cut into strips for pelletizing forlater use in an extruder. The composition prepared as described abovewas formed into strips and these strips were cut into pellets in aconventional pelletizing apparatus.

The pelleted material was later introduced into an extruder having a31/2 inch screw with a 15:1 length to diameter ratio. The compressionratio based on the screw design of the extruder was three to one.

The pelleted material of this example was introduced into the extruderand the composition was extruded onto a conductor. The composition wasextruded onto a #12 AWG 19-strand conductor to form an insulating layerhaving approximately a 0.030 inch wall thickness. The test specimenidentification was ID-92-99-3.

Test data was obtained on the sample by conducting a number of tests.The tests were standard tests employed in the industry in thistechnology. A tensile test which was done on the insulation at 20 inchesper minute according to standard industry practice gave an originaltensile value of 2488 pounds per square inch. The elongation testperformed on the same sample at the 20 inch per minute testing rate gavean elongation value of 414%.

The hot modulus of the material was measured according to establishedindustry practice by which the testing sample is subjected to a hotenvironment of 150° C. for 5 minutes. Then, the force required tostretch the test sample to 100% elongation is measured and the force iscomputed in psi units as a measure of tensile strength. The hot modulusvalue found for this product of Example 1 was 250 psi.

This value of hot modulus is quite surprising, unique and unexpected. Toillustrate the novelty of this result, if the hot modulus of acomposition containing essentially the same ingredients as that ofExample 1 but excluding the PTFE were measured, but the base polymerwere entirely the ethylene-propylene rubber, it is estimated that thehot modulus obtained would be approximately 100 psi. Also, if a samplehaving essentially the same additives as those used in Example 1, buthaving solely high density polyethlyene as the base polymer and havingno PTFE were prepared and tested and the hot modulus measured, it isestimated that the hot modulus of such a material would be approximately100 psi. This value is estimated because it has not been possibleheretofore to produce a wire insulated with chemically crosslinked highdensity polyethylene without the aid of PTFE. Accordingly, it is veryunique and distinctive and surprising to find, when the two materialsare used in combination with a minor amount of polytetrafluorethylene,that a hot modulus of 250 psi is found. It is believed that thedistinctive hot modulus value is due in part to the fact that the uniqueinterdispersing of the high density polyethylene and theethylene-propylene rubber can be and is accomplished as a novelcomposition of this invention, but in addition, that there is aninfluence on the hot modulus which is the result of the presence of thenovel and unique interdispersing agent which is employed and,specifically, the polytetrafluoroethylene.

Another measurement made on the insulation layer formed on the wire ofthis example is the heat distortion at 150° C. The heat distortion is ameasurement of the distortion of the insulation on the wire when a 500gram weight is rested on the wire so that an area of the weightaccording to the established industry standard is bearing on theinsulation. This heat distortion test is measured in terms of thepercent change in the diameter of the wire with the 500 gram weightbearing on the wire. It was observed for the insulated wire as preparedin Example 1 that the heat distortion was 1.64%, or, the insulationdeformed to the extent of 1.64% of the original dimension of theinsulated wire. In other words, the wire with the 500 gram weight on itretained 98.36% of its original diameter. Again, it is a reflection of avery unique and novel combination of properties to be found in a singlecable insulation to have the high values of tensile and elongation asare found for the cable of Example 1, and at the same time, to have sucha low value of heat distortion at the elevated temperature of 150° C. atwhich the heat distortion measurement is carried out and made. As anillustration of the significance of this relatively small value of 1.64%distortion at 150° C., it is a fact that the industry standard for aninsulated wire of the construction of that provided by Example 1 is afull 20% and, accordingly, a value as provided here of only 1.64% isunusually excellent for a wire construction.

Additional tests were conducted concerning the suitability of the wireinsulation formed in accordance with the present invention usingstandard industry tests and it was found that the composition servedsatisfactorily as a wire insulation.

                  TABLE I                                                         ______________________________________                                        COMPOSITION                 PARTS                                             ______________________________________                                        High Density Polyethylene,  20                                                Density = 0.950; Melt Index = 8; Sold by USI                                  Chemical Co. under the trade designation                                      LS506 or MA 778                                                               Semi Crystalline Ethylene Propylene Copolymer,                                                            80                                                Sold by DuPont under the trade designation                                    Nordel 2722                                                                   Polytetrafluoroethylene powder supplied by Du Pont                                                        1.8                                               under the trade designation Teflon 6                                          Crosslinking Agent (2,5 dimethyl-2,4 di[tert-butyl per-                                                    3                                                oxy] hexyne-3) supplied by Penwalt Co. under the                              trade designation Lupersol 130                                                ______________________________________                                    

Nordel is a trademark of the Du Pont Chemical Company. It is applied toelastomers based on an ethylene-propylene-hexadiene terpolymer.

A composition containing the same ingredients as set out in Table Iabove, but excluding the peroxide component, was prepared for injectionmolding by the compounding procedure using the high intensity mixer asdescribed above. The composition was first mixed in a high intensitymixer followed by banding on a mill roll. The material was taken off themill as strip and diced in a conventional dicing maching. The dicedmaterial was fed to an injection molding machine and injection molded asdescribed above to form an injection molded part of about three squareinches area and one-eighth inch thickness.

The product formed was highly pliable and had substantial integrity.

EXAMPLE 2

The composition as described in Example 1 was prepared but the PTFE wasomitted. The composition was placed in a high intensity mixer,specifically a Banbury mixer, and an effort was made to blend theingredients as listed in Example 1 with the exception of the PTFEingredient.

After an extended period of mixing at essentially the same temperatureconditions and time as described in Example 1, the material was droppedfrom the Banbury in bulk form and appeared in bulk to be adequatelymixed. After the first Banbury mixing, the composition was put on themill in order to form sheet of the product and it was there observedthat the material was obviously not homogeneously mixed as evident fromthe roughness of the texture of the material and the surface dryness ofthe material and also the aspersities observed in the material.Nevertheless, the material was formed into a sheet and the sheet wastaken off the mill having a rough texture, very different from thatobserved in the similar step of Example 1. The sheeted material was thenplaced back in the Banbury mixer at a lower temperature and the peroxideadditive as well as the silicone fluid additive were included in thehigh intensity mixer for blending into the composition. After furtherhigh intensity mixing at the lower temperature, the composition wasdropped from the Banbury and again appeared in bulk to have theingredients mixed together satisfactorily.

The dropped composition was placed on a mill and milled to sheet form.The sheet material on the mill again appeared to have quite a roughtexture and a dry surface and was far inferior in its appearance to thecomposition at the same stage as recited in Example 1.

The composition was taken off the mill as strip and the strip was dicedin a conventional dicing apparatus. The diced composition was introducedinto an extruder and the composition was extruded onto wire to form aninsulation.

It was observed that the insulation layer formed by the extruder wasquite uneven and lumpy and had an irregular surface which made it quiteunsatisfactory for use as a cable insulation layer. The tensile strengthof the layer of material was tested after a sample was removed from thewire surface. The tensile measurement indicated that the tensilestrength was less than 1200 psi and, accordingly, only about one half ofwhat was required in the way of tensile strength for a cable to beapplied to the uses for which this cable was intended.

The very poor results obtained in the tensile test and the very poorappearance and the surface roughness, lumpiness and unevenness of thecable insulation indicated that it was not worth running further testson this cable insulation based on prior experience in dealing with theinsulations of many different cables.

EXAMPLE 3A

A set of ingredients, given in proportions of parts by weight, are setforth in Table 11.

The ingredients, other than the peroxide, are introduced into a highintensity mixer which has been preheated to a temperature of 150° F. andare mixed in the apparatus for a period of time sufficient to achieve agood blend and to raise the temperature of the blend due to theimparting of a heat of mixing to the composition as the high intensitymixer operates. When the chart temperature of the composition reachesabout 320° F., the composition is dropped from the high intensity mixerthrough a mechanism built into and normally used for this purpose. Theheat which the composition has received during this temperature rise isthe heat of mixing as in Example 1, and no high temperature externalheat need be applied in order to attain this temperature increase.

The dropped batch of material which has a probe temperature measured byan inserted thermocouple of about 340°-360° F., is then milled on aplastic mill after removal from the high intensity mixer. The materialon the plastic mill is banded and taken off as sheets. The sheet productis allowed to cool and the blending apparatus is also allowed to cool.The sheet material is reintroduced into the high intensity mixingapparatus when the apparatus has a temperature of about 150° F., and acomposition containing 3 parts per hundred of dicumyl peroxide is addedto the composition in the mixer. The contents of the high intensitymixer are mixed and the composition temperature rises due to the heat ofmixing which is imparted thereto. The peroxide containing compositioningredients are mixed into the composition and the temperature isallowed to rise to approximately 240° F., but not to higher temperaturesin order to avoid premature decomposition of the dicumyl peroxide. Thecomposition is mixed in the high intensity mixer to form aninterdispersion of the low density polyethylene and the ethylenepropylene diene monomer, EPDM.

Accordingly, this example provides another demonstration of the uniquecapability of the interdispersing process of this invention to bringtogether what are otherwise and what are normally incompatible polymermaterials in proportions which are incompatible, to yieldinterdispersions and to generate unique materials which have a highdegree of homogeniety.

Following the introduction of the peroxide containing material and theremoval of the compound from the high intensity mixer, it is againrolled on a plastic mill into sheet form and cut into strips forpelletizing for later use in an extruder. The pelletized material whichwas prepared from the composition of this example was later introducedinto the extruder which was described and used in Example 1 above. Thepelleted material was run through the extruder and extruded onto a #12AWG conductor formed of 19 strands. The insulation layer deposited onthis conductor had a thickness of approximately 0.030 inches. The testspecification identification number was ID-92-89-6.

Tests were run on the wire thus prepared and test data was obtained andthe test results are set forth in the accompanying Table II.

EXAMPLE 3B

The composition prepared as described in Example 3A was employed toextrude an insulation layer on a #12 AWG stranded conductor having 19single strands. The thickness of the insulation layer was 45 mils, or0.045 inches. The insulation thus formed was tested and the tensile andelongation values obtained were 1873 pounds per square inch and 294percent, respectively. The sample was tested for crush and abrasionresistance and values of crush of 3460 pounds and abrasion resistance of1171 cycles were found.

EXAMPLE 3C

The composition prepared as described in Example 3A was also used toextrude an insulation coating of 0.075 inches onto a conductordesignated as an MCM 313 conductor. An insulation layer of 0.075 incheswas deposited on the conductor. This layer successfully insulated theconductor.

EXAMPLE 3D

The composition prepared as described in Example 3A was extruded onto aconductor of 646 MCM. The insulation layer deposited was 0.090 mil. Asuccessful insulation of the larger conductor was accomplished.

As used herein, a circular mil is a unit of measurement for thethickness of wires. It is equal to an area of a circle with a diameterof 1 mil. A wire or conductor can be described in terms of the number ofcircular mils which it contains. The designation "MCM" as used hereinmeans thousand circular mils. In other words, it is a measure of aconductor having a cross-sectional area of one thousand circular mils asthe definition of circular mil is given above.

If a conductor is 313 MCM, that means that it has 313,000 circular milsin its cross-section. A conductor with 646 MCM has 646,000 circular milsin its cross-section. This is the cross-sectional area of actualconductor and does not encompass the overall outer dimensions of theconductor nor the space between individual strands of the conductor, butrather is a measure of the total cross-section of conductor in the cableindependently of the stranding or strand size or conductor size of thecable.

                  TABLE II                                                        ______________________________________                                                                  PARTS PER                                           COMPOSITION               HUNDRED                                             ______________________________________                                        Low Density Polyethylene, 30                                                  Density = 0.920; Melt Index = 2.5; Sold by City                               Service Company under the trade designation                                   EH497                                                                         Semi Crystalline Ethylene Propylene Copolymer,                                                          70                                                  Sold by DuPont under the trade designation                                    Nordel 2722                                                                   Polytetrafluoroethylene powder supplied by Du Pont                                                      1.5                                                 under the trade designation Teflon 6                                          Dicumyl peroxide curing agent available commer-                                                         3                                                   cially from the Hercules Company under the trade                              designation DiCup R                                                           Miscellaneous additives   132.5                                               ______________________________________                                    

EXAMPLE 4

The composition as described in Example 3A was prepared but the PTFE wasomitted. The composition was placed in a high intensity mixer,specifically a Banbury mixer, and an effort was made to blend theingredients as listed in Example 3A with the exception of the PTFEingredient.

After an extended period of mixing at essentially the same temperatureconditions and time as described in Example 3A, the material was droppedfrom the Banbury and appeared in bulk to be adequately mixed. After thefirst Banbury mixing, the composition was put on the mill in order toform sheet of the product and it was there observed that the materialwas obviously not well or homogeneously mixed as evident from theroughness of the texture of the material and also the aspersitiesobserved in the material.

Nevertheless, the material was formed into a sheet and the sheet wastaken off the mill having a rough texture, very different from thatobserved in the similar step of Example 3A. The sheeted material wasthen placed back in the Banbury mixer at a lower temperature and theperoxide additive material was included in the high intensity mixer forblending into the composition. After further high intensity mixing atthe lower temperature, the composition was dropped from the Banbury andagain appeared in bulk to have the ingredients mixed togethersatisfactorily.

The dropped composition was placed on a mill and milled to strip form.The material on the mill again appeared to have quite a rough textureand a dry surface and was far inferior in its appearance to thecomposition at the same stage as recited in Example 3A.

The composition was taken off the mill as strip and the strip was dicedin a conventional dicing apparatus. The diced composition was introducedinto an extruder and the composition was extruded onto wire to form aninsulation.

It was observed that the insulation layer formed by the extruder wasquite uneven and lumpy and had an irregular surface which made it quiteunsatisfactory for use as a cable insulation layer. The tensile strengthof the layer of material was tested after a sample was removed from thewire surface. The tensile measurement indicated that the tensilestrength was less than 800 psi and, accordingly, only about one-third ofwhat was required in the way of tensile strength for a cable to beapplied to the uses for which this cable was intended.

The very poor results obtained in the tensile test and the very poorappearance and the surface roughness, lumpiness and unevenness of thecable insulation indicated that it was not worth running further testson this cable insulation based on prior experience in dealing with theinsulations of many different cables.

EXAMPLE 5A EPR/L/DPE; EPR/HDPE; 90/10

The ingredients other than the peroxide containing material wereintroduced into a high intensity mixer preheated to a temperature ofabout 150° C. essentially as described in Example 3. No PTFE wasincluded in this specific composition. After thorough mixing, thecomposition was dropped from the mixer at a temperature of about 290° F.The composition was observed to be relatively coarse and rough in itssurface characteristics, indicating that the complete and intimateintermixing of the ingredients, which had apparently occurred in Example3, had not occured in the material of this Example 5A. There was,however, a low degree of apparent blending, evidently due to the factthat the percentage of the low density polyethylene was relatively lowin this composition and that the EPDM, i.e., the Nordel 2722 ingredient,has an ability to accept and blend with a relatively small amount of thelow density polyethylene without the aid of any agent. The presence ofthe fillers and additives in the composition apparently does aid inestablishing an apparent blend. In the absence of these fillers andadditives, the degree of blending is not nearly as high and a certainamount of delamination or separation of the polymer components isexpected for the unfilled composition.

The dropped compound was put on a mill and taken off in sheet form forlater reintroduction into the high intensity mixer. The high intensitymixer was allowed to cool to about 150° F. and the sheets of compoundwere introduced into the mixer together with peroxide as shown in theTable III.

The composition formed from this high intensity mixing had a finaltemperature of below approximately 240° F. to avoid the prematuredecomposition of the peroxide. The composition was placed on a mill andtaken off in sheets and the sheets were processed through a conventionaldicing machine to form pellets of the peroxide containing compound.

The compound pellets were introduced into an extruder and the compoundwas extruded onto a #12 AWG 19-strand conductor to form an insulatingwall on the conductor having dimensions of approximately 0.030 inches.This wire and its insulation were immediately passed into a conventionalhigh temperature, high pressure curing chamber and were exposed to thesaturated steam of the chamber for a time sufficient to causedecomposition of the peroxide and the crosslinking of the polymercomponents of the composition. The crosslinked wire product was removedfrom the chamber through a water seal in the conventional manner.

EXAMPLE 5B

The procedure as carried out above was repeated for sample 5B with theexception that although all of the other ingredients and ingredientconcentrations were essentially the same as used in Example 5A, 1.5parts of Teflon-6 were added to the composition to form composition 5B.The blending procedure was carried out as described with reference toExample 5A and it was observed that a very smooth, creamy, apparentlyhomogeneous interdispersion of ingredients was formed from the initialmixing and was further formed from the additional mixing with theperoxide containing ingredient.

There was a very noticeable difference in the appearance of thecomposition prepared by this Example 5B, particularly in the surfaceappearance of the compound as the compound was much more uniform andsmooth in its surface appearance, and in its internal appearance whensubjected to a cutting than the composition of Example 5A. The smoothersurface appearance and smoother working of the compound was alsoobservable on the mill as the compound was being sheeted preparatory todicing.

Following the preparation of the composition, it was extruded on a wireas described in Example 5A, and tests were conducted on the wireinsulation. The abrasion test resulted in a finding of a value of 399cycles as compared to the 235 cycles found for Example 5A. This resultedin an increase of approximately 70% in the abrasion resistance of thewire. This increase in the abrasion resistance was attributed to theaddition of 1.5 parts of the Teflon 6 and to the increased homogeneityof the composition which resulted from the addition of the 1.5 parts ofthe Teflon 6.

EXAMPLE 5C

The procedures recited with regard to Examples 5A and 5B were repeatedbut, in this case, with the addition of 3 parts of Teflon 6 to thecomposition as compared to the 1.5 parts in Example 5B and 0 parts inExample 5A. Again, a much more homogeneous and smooth surfacecomposition was found in Example 5C as compared to that from Example 5A.The composition was extruded onto a wire to form a 0.030 inch wallthickness.

An abrasion resistance value of 577 was found on testing and representsan increase over that found for Sample 5B of about 45% and represents anincrease in abrasion resistance over Sample 5A of approximately 145%.Accordingly, this provides a very dramatic illustration of theextraordinary and remarkable influence of the addition of very smallamounts of the Teflon 6 agent to compositions which are used in specificend use applications illustratively in this case in wire insulation. Theapplicants believe that these improvements could be imparted to otherproducts and other polymer systems used in other end use applicationsas, for example, in tires. This conclusion is presented on the basis ofthese examples and on the awareness of the inventors that the abrasionresistance is associated with wear resistance and that by the additionof relatively small percentages of polyethylene, such as the low densitypolyethylene of Examples 5A, 5B and 5C, or the high density polyethyleneof Example 5D below, dramatic increases in the wear resistance of rubberarticles such as tires may be achieved where the relatively lowpercentage addition of the polyolefin is accompanied by the addition ofa very small amount of the uniquely fibrous fluorocarbon blending agenttaught in this invention.

In addition to the observation of the improvement in the abrasionresistance, there is also observation of an increase in the tensile andan increase in the elongation properties of the material with theaddition of small quantities of the uniquely fibrous fluorocarbon agentto form an interdispersion of a smaller portion of polyethylene in alarger portion of the ethylene propylene rubber base polymer.

EXAMPLE 5D

The composition as described in Example 5A, 5B and 5C was prepared, butwith a modification in its polymer content. In fact, the composition isidentical with that in Example 5B except that the 10 parts of lowdensity polyethylene of Example 5B was replaced with 10 parts of highdensity polyethylene and, specifically, 10 parts of high densitypolyethylene identified commercially as TR-955 of the Phillips Company.This high density polyethylene had a density of 0.955 and a melt indexof 8. The composition of this Example 5D also contained the 1.5 parts offluorocarbon.

After a wire was coated with the composition as described in the Example5D, the wire insulation was tested for abrasion resistance and a valueof abrasion resistance obtained is shown in Table III. It is evidentthat the abrasion resistance with the high density polyethylene issubstantially higher than that with the low density polyethylene for thesame percentage of polyethylene intermixed in the EPR and for the samequantity of PTFE interdispersing agent. Specifically, the value of 928for the composition 5D containing 10% HDPE is approximately 132% greaterthan the abrasion resistance for the composition of Example 5Bcontaining 10% LDPE. In addition, it is approximately 300% greater(specifically, 295%) than the value found for the composition of Example5A and, accordingly, the abrasion resistance value measured by the sametest for the composition 5D shows a remarkable increase in abrasionresistance from the addition of the relatively small percentage ofapproximately 10 parts of high density polyethylene and the relativelysmall quantity of approximately 1.5 parts of Teflon 6 to the rubber basepolymer, i.e., to the EPDM.

It should be pointed out that although there is some tolerance of therubber for low density polyethylene, and a certain small percentage oflow density polyethylene can be incorporated in the rubber, althoughwithout achieving the total homogeniety, nevertheless, the rubber,particularly the EPDM, is essentially incompatible in the higher ratiosboth with the low density polyethylene of Examples 5B and 5C, and withhigh density polyethylene of the character employed in this Example 5D.It would not be possible to combine 10 parts of high densitypolyethylene with 90 parts of EPDM using conventional processingequipment and procedures even with all of the ingredients the otheradditives of the Examples 5A-5D because of the basic incompatibility ofthese materials in this higher ratio.

Accordingly, it is very significant and unique that this homogeneousinterdispersion of the combination of materials has been achieved withthe aid of the PTFE interdispersing agent.

                  TABLE III                                                       ______________________________________                                        INGREDIENTS          5A     5B     5C   5D                                    ______________________________________                                        Low density polyethylene, Density =                                                                10     10     10                                         0.92; Melt Index = 2.5; sold by City                                          Service Co. under the trade                                                   designation EH497                                                             High density polyethylene, Density =    10                                    0.955; Melt Index = 8; sold by                                                Phillip Co. under the trade                                                   designation TR-955                                                            Semi Crystalline Ethylene Propylene                                                                90     90     90   90                                    Copolymer, Sold by DuPont under the                                           trade designation Nordel 2722                                                 Miscellaneous Additives                                                                            100.5  100.5  100.5                                                                              100.5                                 Polytetrafluoroethylene powder                                                                      0      1.5    3    1.5                                  supplied by DuPont under the trade                                            designation Teflon 6                                                          Dicumyl peroxide curing agent                                                                       4      4      4    4                                    available commercially from the                                               Hercules Company under the trade                                              designation Dicup R                                                           ______________________________________                                    

EXAMPLE 6

Several compositions were prepared in the manner similar to thatdescribed in Example 5. The ingredients included 20 parts of highdensity polyethylene for some of the compositions, and 30 parts of highdensity polyethylene for other of the compositions with the remainderbeing an EPDM copolymer or, more specifically, a terpolymer elastomermade from ethylene-propylene diene monomer. The compositions wereprepared essentially as described in Example 5 and each contained 1.5parts of Teflon 6.

The compositions were, in fact, quite similar to the composition ofExample 5D in that the combination of high density polyethylene and anEPDM copolymer were interdispersed according to Example 5D and accordingto this example. In Example 5D, 10 parts of the high densitypolyethylene were employed whereas in this example 20 and 30 parts ofthe EPDM were employed. The testing of the peroxide crosslinkedcomposition, which had been extruded onto wire as described in Example5D, gave abrasion test values of 1135 strokes and 1471 strokes,respectively, for the interdispersed composition containing 1.5 parts ofPTFE and 20 parts of high density polyethylene and 1.5 parts of PTFE and30 parts of high density polyethylene. Accordingly, it is seen that themost rapid increase in the abrasion resistance of the interdispersedcomposition which results from the interdispersion of the high densitypolyethylene occurs with the first 10% addition of high densitypolyethylene into the interdispersed composition aided by the 1.5 partsof PTFE interdispersing agent.

EXAMPLE 7A LDPE/HDPE

Fifty parts of low density polyethlyene were placed on a conventionalsmall laboratory plastic mill having preheated rolls. The smalllaboratory mill had two rolls of about 3 inch diameter each and about 6inches of exposed roll surface. One of the two rolls was rotated about50% faster than the other to induce significant shearing of the milledmaterial as it passed through the nip of the rolls. Heating was byheated oil passing through the interior of the rolls from conventionalheating means.

A small quantity of less than about one part of an antioxidant,specifically Flectol H, was added to the banded low density polyethyleneto inhibit oxidative degradation of the low density polyethylene.

After the polyethylene containing the antioxidant was banded on themill, 50 parts of high density polyethylene were added to the nip of therolls.

Some apparent blending of the low density polyethylene and high densitypolyethylene took place based on visual observation of changes to thetwo polymer ingredients, but the apparent blending was not at allcomplete.

EXAMPLE 7B

1.8 parts of Teflon 6 were added to the composition of Example 7A and acomposition having an appearance and an apparent cohesion superior tothose of Example 7A were observed. The applicants interpreted theseimprovements in composition appearance to evidence formation of at leastpartial interdispersion of the two polymers.

EXAMPLE 8A LDPE/LLDPE

Fifty parts of low density polyethlyene were placed on a conventionalsmall laboratory plastic mill as described in the previous example.

A small quantity of less than about one part of an antioxidant,specifically Flectol H, was added to the banded low density polyethyleneto inhibit oxidative degradation of the low density polyethylene.

After the polyethylene containing the antioxidant was banded on themill, 50 parts of linear low density polyethylene were added to the nipof the rolls.

Some apparent blending of the low density polyethylene and linear lowdensity polyethylene took place based on visual observation of changesto the two polymer ingredients, but the apparent blending was quitelimited.

EXAMPLE 8B

1.8 parts of Teflon 6 were added to the composition of Example 8A and acomposition having an appearance and an apparent cohesion superior tothose of Example 8A were observed to form. The applicants interpretedthese improvements in composition appearance to evidence formation of atleast partial interdispersion of the two polymers.

EXAMPLE 9 HDPE/PVC

The procedures and apparatus of the prior example were employed todetermine by visual observation whether a blend and whether aninterdispersion formed from the combination of a binary pair ofingredients on a heated plastic mill as set forth below.

EXAMPLE 9A

An attempt to blend high density polyethylene and polyvinyl chloride ina 50/50 ratio without Teflon 6 was made. Some very minor apparentblending took place.

EXAMPLE 9B

1.8 parts of Teflon 6 were added to the composition of Example 9A andfurther milling under the same conditions as used in Example 9A wascarried out. Vastly improved homogeneity of the composition, improvedappearance and cohesion were observed, thus indicating formation of aninterdispersion.

EXAMPLE 10 LDPE/EPR

The procedures and apparatus of the prior examples were employed todetermine by visual observation the effect of mixing on a plastic mill,as described in the examples above. a combination of low densitypolyethylene and ethylene propylene rubber, both without and withinterdispersing agents.

EXAMPLE 10A

An attempt was made to blend low density polyethylene and ethylenepropylene rubber (EPDM 1145) in a 50/50 ratio on a plastic mill havingrolls heated to 220° F. Some apparent blending took place.

EXAMPLE 10B

Example 10A was repeated, except ultra high molecular weightpolyethylene (Hercules UHMWPE 1900, Intrinsic Viscosity 22, estimatedmolecular weight over 3 million) powder was added to the composition asan interdispersing aid. Some improvement in the appearance and apparenthomogeneity and apparent processability was noted. This improvementindicated to the observer the formation of at least some interdispersionof the set of polymer ingredients.

Also noted was that a sognificant amount of the UHMWPE 1900 powderparticles had not dispersed into the milling material.

EXAMPLE 10C

Example 10B was repeated, using a higher (300°F.) mill roll surfacetemperature. This temperature was intended to be well above the reportedsintering temperature (about 265° F.). The properties of the compositionwere observed visually to be further improved over that of Example 10B.

EXAMPLE 10D

Example 10C was repeated, except that 1.8 parts of UHMWPE 1900 wasreplaced with 1.8 parts high molecular weight polyethylene (HerculesHMWPE HB 301, Intrinsic Viscosity 10, estimated molecular weight aboutone million). Visual improvement of the composition such as thatobserved in Example 10C was also observed in this example.

EXAMPLE 10E

The mill temperature was lowered to 220° F. and 2.5 parts of Dicipperoxide added to each of the above examples, followed by compressionmolding for 30 minutes at 350° F. into cured slabs.

EXAMPLE 11 LDPE/PVC

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether property improvement occurredfrom an attempt to blend and from an attempt to interdisperse a binaryset of ingredients on a heated plastic mill as set forth below.

EXAMPLE 11A

An attempt was made to blend low density polyethylene and polyvinylchloride in a 80/20 ratio on a 300° F. mill. Included was 1.5 parts ofFlectol H and 10 parts dibasic lead phthalate. Very poor, if any,blending was observed to take place.

EXAMPLE 11B

Example 11A was repeated, except 1.8 parts of ultra high molecularweight polyethylene (Hercules UHMWPE 1900) was added as aninterdispersing aid to the composition. Visual improvement in thecomposition properties was noted, along with improved handlingcharacteristics. This visual improvement was interpreted to indicate theformation of an interdispersion.

EXAMPLE 11C

Example 11B was repeated, except that 1.8 parts of high molecular weightpolyethylene (HMWPE Hercules HB 301) was used as the interdispersingaid. Again noted was visual improvement in the composition propertiesover those observed for the composition of Example 11A, along withimproved handling characteristics. This visual improvement was alsointerpreted to evidence the formation of an interdispersion.

EXAMPLE 11D

The mill temperature was lowered to 240° F. and 1.5 parts of triallylcyanurate plus 1.7 parts of Vulcup peroxide were added to each of theabove examples. The composition was removed from the mill followingmilling, followed by compression molding for 30 minutes at 350° F. intocured slabs.

EXAMPLE 12A HDPE/PTFE/UHMWPE/HMWPE

On a 300° F. mill was banded 100 parts of high density polyethylene and1.5 parts of Flectol H to give a very soft mass of material which stucktenaciously to the mill rolls. Then, Teflon 6 was added and distributedin increments to determine what level of Teflon 6 was needed at this hot300° F. mill roll surface temperature to overcome the stickiness and todry or unstick the material from the mill rolls for reasonable handling.It was found that the addition of 3.5 parts Teflon 6 to the high densitypolyethylene gave an acceptably low level of stickiness.

EXAMPLE 12B

Example 12A was repeated except that ultra high molecular weightpolyethylene (UHMWPE Hercules 1900) was added and distributed inincrements to determine what level of UHMWPE was needed to arrive atabout the same lower level of stickiness or dryness as the 3.5 parts ofTeflon 6. In overcoming stickiness of the HDPE material, it was found tobe about 14 parts of UHMWPE.

EXAMPLE 12C

Example 12B was repeated except that high molecular weight polyethylene(Hercules SB 301) was used to overcome stickiness. It was found thatabout 20 parts of high molecular weight polyethylene were needed toapproximate the level of dryness achieved by the 14 parts of UHMWPE inovercoming stickiness. Even then, the HMWPE did not seem to confer thesame degree of "green strength" or handling properties as the UHMWPE.

EXAMPLE 13

Based on the results obtained in the earlier examples, it becameapparent that the polytetrafluoroethylene (Teflon 6) was an effective,beneficial interdisperser of combinations of polymers, both as preparedand as crosslinked, both in absence and in presence of filler. The sameTeflon 6 was employed in this example toward the interdispersing on aplastic mill of two polymers which normally are poorly blendable. In thepresent example, 50 parts of low density polyethylene are interdispersedwith 50 parts of ethylene-propylene rubber (EPDM Nordel 1145). Accordingto the experience of the applicants, the formation of a blend of theseingredients in this proportion is not feasible employing ordinaryprocessing techniques.

EXAMPLE 13A

The 50 parts of low density polyethylene were banded on a two-roll millof 220° F. roll surface temperature and 1.5 parts of Flectol Hantioxidant was added to minimize shear degradation of the polymer.

Fifty parts of EPDM Nordel 1145 were added to the mill and althoughintermixed well and long, the composition would not form a smoothwell-knit band, but rather formed a band with aspersities anddiscontinuities and a rough, uneven appearance to the unaided eye.

Then, 2.5 parts of dicumyl peroxide were admixed into the composition,which admixture did not significantly change the texture or appearanceof the material on the mill. Thus, from visual observation, it wasapparent that good blending did not occur but that a rough texturedsemi-coherent band of the material was obtained.

This was removed from the mill and formed into a convenient flat piecefor convenience of handling by quickly cooling under a flat metalsurface. The sample was then weighed and one-fourth of the sample wasremoved by cutting and the fourth was retained as a sample. The samplehad a rough, curd-like appearance, was fairly stiff, and broke orfriated easily. There were curd boundaries evident and there wereopenings in the sample measuring approximately 1/8 inch in diameterextending entirely through the sample.

EXAMPLE 13B

The three-fourths of the sample remaining was rebanded on the hot milland 1.8 parts of the polytetrafluoroethylene were added based on theweight of the material on the mill. It was observed that the compositionbecame much more dense and better knit than the Example 13A. Whenremoved from the mill and flattened into a sheet, the sample appearedvery coherent and was able to be flexed without any fracture or breakingoff of portions of the sample. This demonstrated that thepolytetrafluoroethylene clearly served as an interdispersing aid tointerdisperse the components in the 50/50 proportion which had beendemonstrated in Example 13A to be incompatible and poorly blendable atbest. The proportions of the parts per hundred are listed in the Tablefor Example 13.

The material was weighed and one-third was removed by cutting and thiscut portion was retained as a sample.

EXAMPLE 13C

The remaining two-thirds was rebanded on the same hot mill. It wasnoteworthy that rebanding was accomplished much more readily than wasthe material of Example 13A. Then, twenty parts of treated clay,Translink 37, were easily incorporated into and uniformly dispersedthroughout the material banded on the mill. The sample was then removedfrom the mill, formed into a convenient flat piece, weighed, andone-half retained as a sample.

EXAMPLE 13D

The remaining half was rebanded on the hot mill and an additionaltwenty-five parts of the clay were added to the material on the mill andworked on the mill until the composition had achieved apparentuniformity of distribution of the clay filler. The resulting compositionhad a total of 45 parts of clay along with the other ingredients aslisted in the table. Then, the material was removed from the mill,flattened and saved.

One general observation drawn from the Example 13 is that the banding orrebanding of an attempted blend or mix of the low density polyethylenewith ethylene-propylene rubber is a difficult process. When the processis compared to an effort to accomplish the same rebanding by placing asample having the polytetrafluoroethylene already distributed in thesample onto a mill, it is apparent that the material containing thepolytetrafluoroethylene processes and handles much better. The presence,in other words, of the polytetrafluoroethylene in the composition makesthe workability and in this case the rebanding of material on a millmuch simpler and more expeditious.

The Applicants view such improved rebanding ability as indicative ofmuch greater cohesion of the gross piece which is believed to persistdown through the molecular domain indicating improved intermingling ofmolecules of the different polymer types making up the interdispersionformed.

EXAMPLE 13C

Another apparent difference between samples which contain PTFE and thosewhich do not is that when the cold material without the PTFE was placedon the hot mill to be re-banded, it quickly fragmented and fell off therolls and the fragment needed tedious cycling by hand until thefragments softened and banded. However, when the same material contained1.8 parts of Teflon 6, it underwent rebanding much more easily byentering into the nip of the roll with little or no fragmentation andallowing itself to be gradually melted right onto the roll. This is amuch better "re-banding" of the original material, or better feeding,re-fluxing, and re-melting characteristics.

This indicates that there will be a much better behavior of the materialfluxing and extruding than is the case where the Teflon 6 is absent andthat the addition of only a very small amount of PTFE to interdispersedpolymers to be processed will result in significant processingimprovements as equivalents of the processing improvements observed inthe examples below.

Well interdispersed polymer material does undergo very extensivestretching and where such a material contains a peroxide crosslinkingagent dispersed therein, it is deemed possible to stretch the materialinto a thin film or into a fiber and to crosslink the film or fiber bythe heating of the stretched composition to a temperature above thedecomposition temperature of the contained peroxide.

    ______________________________________                                        TABLE FOR EXAMPLE 13                                                                           13A  13B     13C    13D                                      ______________________________________                                        Low density polyethylene, Exxon                                                                  50     50      50   50                                     LD 83.9 pellets                                                               Ethylene-propylene rubber, sold                                                                  50     50      50   50                                     by Du Pont under the trade                                                    designation Nordel 1145EPDM                                                   Antioxidant additive,                                                                            1.5    1.5     1.5  1.5                                    polymerized trimethyl                                                         dihydroquinoline, sold under                                                  the trade designation Flectol H                                               Dicumyl peroxide curing agent                                                                    2.5    2.5     2.5  2.5                                    available                                                                     commercially from the Hercules                                                Company under the                                                             trade designation DiCup R                                                     Polytetrafluoroethylene powder                                                                          1.8     1.8  1.8                                    supplied by DuPont under the                                                  trade designation Teflon 6                                                    Mineral Filler Additive           20   45                                     (silicone treated clay as                                                     described in U.S. Pat. No.                                                    3,148,169) and supplied by                                                    Freeport Kaolin Corp. under the                                               trade designation Translink 37                                                ______________________________________                                    

EXAMPLE 14 LDPE/EPR/NR

A set of ingredients were prepared for processing on the mill asdescribed in the above examples.

EXAMPLE 14A

Thirty-three parts of low density polyethylene were fluxed on a two rollmill having a 220° F. mill roll surface temperature and Flectol Hantioxidant was added. Thirty-three parts of ethylene-propylene rubberwere then added to the fluxing low density polyethylene on the mill,giving a composition on the mill which resembled that of Example 7A.

2.5 parts of dicumyl peroxide were then added to the fluxing low densitypolyethylene and ethylene-propylene rubber on the mill and were blendedinto the composition. It still retained the coarse, curdy, poorly knitappearance of the composition of 7A.

Thirty-three parts of natural rubber were added to the compositionbanded on the mill. It was observed that the character of the bandedcomposition on the mill changed from the coarse, rough, poorly knit,curdy material to a smooth, homogeneous, dense, cohesive compositionwhich milled nicely and that this occured in a relatively short time andin a manner somewhat analagous to the way in which the PTFE brought thecoarse, curdy composition of sample 13A into the smooth, cohesive, densecomposition of sample 13B.

It was also observed that there was a similarity between the characterof the material banded on the mill in its grain effect, i.e., thetendency to display greater resistance to stretching in the mill rollperipheral direction as contrasted with a lateral or roll axis directionand the grain effect of the material of sample 7A, and in the degree ofextensibility of the material, particularly when worked with animplement such as a mill knife, in order to work the batch in a normalmanner of bringing the outer edges of the composition in toward thecenter and the like.

As used herein, the term "grain effect" means a very distinctly visuallyobservable orientation of the material on the mill, preferentially inthe mill direction. The grain effect may be ilustrated, for example, byplacing a tool under one edge of the material and then wedging the toolaway from the surface of the mill and having the composition ride outfrom the mill over the tool and back onto the mill, showing a strongcohesivenes of the material in the direction in which it is beingmilled.

Another illustration is that if the mill is stopped and a lateral cut ismade in the direction axial to the mill roll, the tendency of thematerial to pull back from the cut surface and to separate, giving anopening of the cut as it is performed, occured both with thePTFE-bearing materials of the earlier examples and with the naturalrubber-bearing material of this Example 14A. This similar behavior ofthe two different materials leads to a possible conclusion that there isa relationship between the materials which relate to this grain effector orientation of the materials of the composition.

From observation of this sample 14A in its behavior on the mill withoutany PTFE content and from observation of a sample such as 14B which didhave PTFE, it was concluded that the surprising blending together of thenon-cohesive, curdy, coarse composition of Example 14A both responsiveto the PTFE in very small percent of approximately 1.8 parts and to thenatural rubber in substantially high percentage of 33 parts, may arisefrom a similar mechanism which relates to the interraction on amolecular scale of the natural rubber with the two ingredients andsimilar interraction of the PTFE with the two disimilar ingredients,namely, the low density polyethylene and the ethylene-propylene rubber,of sample 13A.

In this example, it is deemed by the inventors that an interdispersionof low density polyethylene and ethylene propylene rubber was induced bythe addition of the natural rubber at the 50% level relative to thepolymer ingredients to be interdispersed.

EXAMPLE 14B

The composition of Example 14A was removed from the mill and formed intoa convenient flat piece which was then weighed and one-fourth of thematerial was removed and saved as a sample.

The remaining three-fourths of the composition of 14A were placed on themill and banded to flux smoothly on the mill. 1.8 parts ofpolytetrafluorethylene were added to the composition on the mill and itwas observed that this PTFE was absorbed very rapidly into thecomposition which was banded on the mill. Both the takeup of the PTFEand the dispersion of the PTFE in the composition were quite rapid incomparison to the other samples to which the PTFE was added in likequantity.

The composition of Example 14B was removed from the mill. It wasobserved in removing the material from the mill that the cutting of thematerial against the grain and in the direction parallel to the rollaxis gave a separation of the sample similar to that which occured forExample 14A and that the difference between the separation as occured inthis example and that which occured in 14A was not great as contrastedwith the great difference which did occur when PTFE was added to 13A toform 13B.

It was observed as the material fluxed on the mill that there were nonodes formed parallel to the axis of the rolls, nor were there anystring-like structures stretching across the nodes inasmuch as therewere no nodes formed. This was a distinct difference from thecomposition of Example 13B which did show both the nodes runningparallel to the nip of the rolls and also the string-like structureswhich were perpendicular to the nodes.

The sample 14B was removed from the mill and quickly formed into aconvenient flat piece.

The piece formed in Example 14B was weighed and one-third of the piecewas removed and saved as a sample for test and observation.

EXAMPLE 14C

The remaining two-thirds of sample 14B was rebanded on the hot mill and20 parts of Translink 37 (silicone treated calcined clay filler) wereadded and distributed therein, after which the material was removed andformed into a convenient flat piece.

After the additive was completely interdispersed, and the materialworked on the mill for a time, the sample was removed, quickly formedinto a flat piece and weighed.

EXAMPLE 14D

One-half of the material produced as Example 14C was removed and theremainder was rebanded on the hot mill. Then, 25 additional parts of thetreated clay were added to bring the total in Example 14D to 45 parts oftreated clay. After working to uniformity, the material was removed,quickly formed into a flat piece and saved as a sample.

    ______________________________________                                        TABLE FOR EXAMPLE 14                                                                           14A  14B     14C    14D                                      ______________________________________                                        Low density polyethylene,                                                                        33     33      33   33                                     sold by Exxon under the trade                                                 designation LD-83.9                                                           EPDM rubber sold by E. I. Du                                                                     33     33      33   33                                     Pont under the trade                                                          designation Nordel 1145                                                       Natural Rubber     33     33      33   33                                     Antioxidant additive,                                                                            1.5    1.5     1.5  1.5                                    polymerized trimethyl                                                         dihydroquinoline, sold by                                                     Monsanto Chemical Corp. under                                                 the trade designation Flectol H                                               Dicumyl peroxide curing agent                                                                    2.5    2.5     2.5  2.5                                    available                                                                     commercially from the Hercules                                                Company under the                                                             trade designation DiCup R                                                     Polytetrafluoroethylene Powder                                                                          1.8     1.8  1.8                                    supplied by DuPont under the                                                  trade designation Teflon 6                                                    Mineral Filler Additive           20   45                                     (silicone treated clay as                                                     described in U.S. Pat. No.                                                    3,148,169) and supplied by                                                    Freeport Kaolin Corp. under the                                               trade designation Translink 37                                                ______________________________________                                    

EXAMPLE 15A LDPE/Neoprene

Using the procedure of Example 13, a composition was prepared on a millto contain 50 parts of low density polyethylene, 50 parts ofchloroprene, Neoprene type W, as well as 1.5 parts of Flectol H, 2.5parts of dicumyl peroxide, 3.0 parts of dibasic lead phthalate. A roughsurface was observed indicating poorly mixed or blended constituents.The composition was taken from the mill and one-fourth was removed.

EXAMPLE 15B

The remaining three-fourths was placed back on the hot mill, rebanded,and 1.8 parts of Teflon 6 were added and dispersed therein. A noticeableimprovement in the texture of the material on the mill was observed,indicating that greater homogeneity of the composition was achieved withthe addition. of the Teflon 6.

The reduction of the coarse texture and improvement in compositionappearance was taken to be evidence of formation of an interdispersionof the host polymers.

EXAMPLE 15C

The material was removed from the mill and one-third was taken off andsaved as a sample and the remaining two-thirds was returned to the mill.Twenty parts of Translink clay were added as described in earlierexamples and were found to blend well into the composition.

EXAMPLE 15D

The composition was again removed from the mill and half of it was savedas a sample and the remaining half was rebanded on the hot mill.Twenty-five additional parts of Translink 37 clay were added and wereobserved to incorporate well into the composition, after which thematerial was removed and saved as a sample.

EXAMPLE 16A

The procedure of example 15 was repeated but in this case, the dibasiclead phthalate constituent was omitted. In all other respects, theprocedure of Example 15 was repeated. The sample of material preparedwithout the Teflon 6 ingredient was observed to be coarse and rough andsomewhat lumpy in character.

EXAMPLE 16B

The samples prepared with the Teflon 6 showed evidence of greaterhomogeneity and the formation of an interdispersion.

EXAMPLE 17A LDPE/SBR

The procedure as described in the previous example was again repeated,but in this case, the polymer ingredients of the test were low densitypolyethylene and styrene-butadiene rubber in a 50:50 ratio. It wasobserved that the sample which was prepared without the Teflon 6 had arough and uneven character and from visual observation had pooreruniformity of dispersion of the ingredients thereof.

EXAMPLE 17B

By contrast, the samples which were prepared to contain the Teflon 6evidenced smoother and apparently more homogeneous and uniformcompositions. This change in the appearance of the compositions fromrough to homogeneous was interpreted as the inducement by the PTFE ofthe formation of an interdispersion.

EXAMPLE 18 LDPE/Silicone Gum

The procedure of the previous example was repeated in all respects otherthan that the ingredients which were placed on the mill in the 50/50ratio were low density polyethylene and silicone gum, particularly,SE-33 silicone gum commercially available from the General ElectricCompany.

EXAMPLE 18A

The procedures as described in the previous example and examples wererepeated and it was observed that the sample which was prepared withoutthe Teflon ingredient had a much more uneven and non-homogeneousappearance based partly on the surface irregularities and apparentlumpiness of the ingredients.

EXAMPLE 18B

By contrast, the samples prepared to contain 1.8 parts of Teflon 6 wereobserved to be much smoother of surface and were apparently much morehomogeneous in their composition.

EXAMPLE 19 LDPE/Block Copolymer

The procedure described with reference to the previous example andexamples was again repeated in all respects, except that the polymericconstituents were low density polyethylene and a block copolymer ofstyrene and butadiene, specifically Kraton G-1652 (availablecommercially from the Shell Oil Company). The composition of the firstportion (19A) which omitted the Teflon 6 was somewhat rougher and drierin its appearance from the material which did not contain the Teflon 6(19B) to the extent of 1.8 parts.

Moreover, on the mill, the portion (19B) which contained the Teflon 6was observed to be very strong in comparison to the sample 19A which didnot contain the Teflon. The samples 19B, C and D could be drawn out andstretched much more easily than sample 19A and, in fact, the sample 19Awould separate and break if an attempt were made to extend it and pullit into a film form to the same degree that the sample 19B, for example,was stretched and pulled.

A noteworthy observation is that the presence of block copolymer ofstyrene and butadiene appeared to enhance the rate at which Teflon 6 wastaken up and dispersed.

EXAMPLE 20A LDPE/PVC

Fifty parts of low density polyethylene were placed on a mill of about270° F. roll surface temperature and thereupon fluxed into a continuousband while 1.5 parts of Flectol H antioxidant were added to stabilizethe polymer against shear degradation.

Then, 50 parts of powdered polyvinyl chloride (Goodrich Geon 30 PVC)were added along with ten parts of dibasic lead phthalate, whichfunctions as a stabilizer for PVC. The result was a mixture composed ofthe white original fine PVC particles, distributed throughout the moltenpolyethylene matrix. The mixture cut very easily with a mill knife, andcuts made axially to the rolls did not tend to open further, indicatinga low order of strength and extensibility. When removed from the milland cooled, the mixture seemed grainy, rough to the touch, and easy tobreak. Even without magnification, the separate original particles ofPVC were readily apparent. The sample was weighed and one-half removedand saved.

A sample of such a 50/50 LDPE/PVC composition, when pressed into a slaband cut into a long strip of about equal width and thickness, can beignited at one end and when so ignited and held in a vertical positionwith the flame at the upper end, will continue to burn and will not selfextinguish.

EXAMPLE 20B

The remaining half of the sample was rebanded on the same 270° F. milland 1.8 parts of powdered polytetrafluoroethylene, availablecommercially as Teflon 6, were then added to the material on the mill.The composition rapidly changed in appearance from grainy to smooth andafter a thorough distribution and fillibration of the PTFE had takenplace, the sample was removed from the mill. Under 10× magnification,the surface of the composition was very smooth and the very prominentdisplay of original PVC particles which had been present in Example 20Awere gone, evidently well interdispersed with the polyethylene.

The occurrence of dynamic nodes in the nip of the mill rolls wasobserved in Example 20B, but was not observed in Example 20A. Bymanipulating the nip clearance, the nodes could be made to form anddynamically bridging across such nodes could be seen very finecobweb-like filaments. By stopping the mill and gently cutting out aportion of the nip area, which was allowed to carefully cool, it waspossible to get a permanent "stop-action" specimen showing theseultra-fine bridging elements for study and characterization.

It is the Applicants experience that polyvinyl chloride (PVC), such asis used in this example, has a normal processing temperature which isbetween 350° F. and 400° F., depending on the processing being carriedout, and that a processing to form a blend of PVC with another materialwould normally be above 370° F. or higher, i.e., PVC with chlorinatedpolyethylene.

However, as is made evident by this example, the interdispersing of PVCwith polyethylene according to the method and teaching of this inventionis at a temperature about one hundred degrees below the anticipatedtemperature at which PVC is usually blended with some other ingredientwith which it is naturally compatible and blendable. There are very fewmaterials with which PVC will form natural blends and chlorinatedpolyethylene is one of the very few.

PVC is believed to be a relatively highly glassy polymer having a widesoftening temperature range rather than a classical melting point atwhich a material abruptly becomes highly fluid. The PVC polymer itselftends to decompose rather than to melt to a low viscosity fluid state asthe temperature is raised.

Pursuant to the present invention, PVC as illustrative of more glassypolymers is interdispersed at temperatures below the normal working orprocessing temperature of such polymers by addition of a small amount ofPTFE to the glassy polymer and by interdispersing with another polymer,in this illustrative example with low density polyethylene.

Accordingly, this example suggests that the more glassy polymers can beinterdispersed with other polymers with the aid of PTFE. It also teachesthat the effective processing temperatures of more glassy polymers canbe lowered in the formation of the interdispersion of PVC and lowdensity polyethylene (LDPE) pursuant to this example at a temperatureabout one hundred degrees below the normal blending temperature.

In a separate interdispersing of PVC powder in LDPE as described above,it was found that an effective interdispersion could be formed at a rollsurface temperature of 255° F. While on the mill, the composition alsodisplayed the increased tendency to stretch into film. Also, when thebanded composition containing the PTFE dispersed therein in fibrous formwas cut axially to the mill roll with a mill knife, the cut edgesseparated spontaneously and drew back slightly, thus indicatingextensibility and a tension in the interdispered composition extendingcircumferentially around the mill roll.

A sample of such a 50/50 LDPE/PVC composition which has beeninterdispersed with PTFE and formed into a long strip of dimensionsabout the same as those described in Example 20A and by the same methodwas ignited and held in a vertical position with the flame at the upperend. In contrast with the results found in Example 20A, the compositionof this example 20B self extinguished. Also, when reignited, theinterdispersed composition again self extinguished.

EXAMPLE 20C

Approximately one-half of the sample prepared in accordance with Example20A was cut from the sample and placed on the mill at approximately 220F mill roll temperature. After the material had reached temperatureequilibrium and was fluxing on the mill, 1.4 parts of a peroxide curingagent, specifically Vulcup R, was added to the mill and was introduceduniformly by the mill agitation into the composition.

After uniform distribution of the peroxide in the sample, it was removedfrom the mill and flattened to a flat sample on a hard work surface. Itwas then introduced into a compression molding press, preheated to atemperature of 350° F. The sample was sandwiched between the two mylarsheets as is conventional practice in pressing such samples in acompression molding press. The pressing was continued for approximately30 minutes at the 350° F. temperature and then the mill was allowed tocool with the sample in place to about room temperture with the aid ofcooling water on the press. The slab sample thus produced measuredapproximately 4 inches by 4 inches. The cured slab was removed and wasobserved to have a generally mottled gray appearance. Close examinationof the sample revealed that there are many, many black specks which arevisible to the unaided eye. There were also white specks as well as somebluish-colored areas associated with and generally surrounding the blackspecks, both of which were visible to the unaided eye and at 10×magnification. There is some overall appearance of non-uniformcoloration of the material, principally because of differentconcentrations of the black specks and blue areas in different locationsof the sample surface.

On an approximate basis, the black specks and some blue colored areasare deemed to correspond roughly to the occurrence of the white specksin the sample 20A before the curing step. The white specks in sample 20Aare undispersed PVC particles and these particles retain to a largedegree the generally spherical or particulate shape which they had whenthey were introduced into the material in Example 20A.

EXAMPLE 20D

Approximately one-half of the material prepared in accordance withExample 20B was placed on a mill having a surface roll temperature ofabout 220° F. and was fluxed on the mill until thermal equilibrium hadbeen reached.

The material on the mill was fluxed at the 220° mill temperature. It wasobserved that this material, although it had originally been prepared at270° mill temperature to uniformly disperse the ingredients,nevertheless was refluxed at the lower 220° temperature without anyevidence of segregation, exfoliation or separation of the ingredientsthereof during the fluxing on the mill.

After the material was fluxed until an essentially uniform temperaturehad been achieved, 1.4 parts of a peroxide curing agent, specificallyVulcup R, was added to the material in the mill and distributed into thecomposition by the milling action on the composition. After the peroxidewas uniformly distributed into the composition, it was removed from themill and pressed on a hard work surface to a flat sample. The sample wasthen introduced into and heated in a compression molding press at 350°F. for approximately 30 minutes, sandwiched between two mylar sheets.The mill was cooled by internal water flow to approximately roomtemperature before the sample was removed from the press. Visualobservation of the sample prepared in accordance with Example 20C andthat prepared in accordance with this Example 20D revealed that whereasthe 20C sample was gray, having small blue-colored areas, havingnon-uniformity of color, having black specks and having white speckswhich were apparent both with the unaided eye and with magnification,that the sample prepared pursuant to this Example 20D appeared to be anattractive apricot or flesh color, generally light in shade and clear incomplexion to the unaided eye. The sample was highly flexible and didnot give any evidence of breaking with folding and other manipulationand appeared fairly stiff. This is in contrast to the material ofExample 20C which broke easily when folded.

EXAMPLE 20E

The overall procedure that gave Example 20D was repeated with the oneexception that there was an additional constituent added. namely 1.5parts of triallyl cyanurate (TAC). The overall outcomes of 20E and 20Dwere highly similar. The TAC crosslinking coagent is believed to enhancethe covulcanization of the PVC with the polyethylene.

    ______________________________________                                        TABLE FOR EXAMPLE 20                                                                          20A  20B    20C    20D  20E                                   ______________________________________                                        Low density polyethylene, sold                                                                  50     50     50   50   50                                  by Exxon under the trade                                                      designation 83.9                                                              Polyvinyl chloride, sold by                                                                     50     50     50   50   50                                  Goodrich under the trade                                                      designation Geon 103                                                          Dibasic lead phthalate                                                                          10     10     10   10   10                                  Antioxidant additive,                                                                           1.5    1.5    1.5  1.5  1.5                                 polymerized trimethyl                                                         dihydroquinoline, sold by                                                     Monsanto Chemical Corp. under                                                 the trade designation Flectol H                                               Polytetrafluoroethylene powder                                                                         1.8         1.8  1.8                                 supplied by DuPont under the                                                  trade designation Teflon 6                                                    Peroxide crosslinking agent,    1.4  1.4  1.4                                 sold by Hercules Company under                                                the trade designation Vulcup R                                                Triallyl cyanurate (TAC)                  1.5                                 ______________________________________                                    

EXAMPLE 21 LDPE/PVC; 50/50

The procedures and materials used in Example 20A and 20B were repeatedbut, in this example, UHMWPE (ultra high molecular weight polyethylene)was used in place of PTFE.

EXAMPLE 21A

Fifty parts of low density polyethylene were placed on a mill with aroll surface temperature of about 300° F. and fluxed to a band. 1.5parts of Flectol H antioxidant were milled into the polyethylene.

Fifty parts of powdered polyvinyl chloride (Goodrich Geon 30 PVC) wereadded to the polyethylene fluxing on the mill together with ten parts ofdibasic lead phthalate.

A mixture formed as described in Example 20A and was removed from themill. A portion was saved for use in Example 21B.

A portion of the sample 21A was pressed into a slab and an elongatedstrip of about equal thickness and width was cut from the slab. Twomarkings were placed on the strip separated by 25 millimeters.

The strip was ignited above the upper mark and the strip was held withthe flame at the top. A measurement was made of the time it took for theflame to burn down the strip between the two marks.

In a first test, the composition self extinguished after 39 secondsafter 6 millimeters had burned and remained to be burned. One dropformed and dropped during the first burning period.

The strip was reignited and burned down an additional 11 millimetersbefore again self extinguishing. Another drop had formed and fallenduring the second burning period which lasted until 108 seconds totalhad passed.

The strip was reignited and burned down the remaining 8 millimeters ofthe initial 25 millimeters. A total lapsed time of 132 seconds forburning the entire 25 millimeters was recorded.

Two additional strips was similarly burned and the results are listed inthe Table for Example 21.

    ______________________________________                                        TABLE FOR EXAMPLE 21A                                                                 IGNI-                                                                         TION*     SEC-              Cumulative                                TEST    FIRST**   OND***    THIRD   Burning Time                              SAMPLE  mm      sec.  mm   sec. mm   sec. To 25 mm                            ______________________________________                                        21A - 1 19     39      8   108          132 seconds                           21A - 2 13     54                        90 seconds                           21A - 3 18     43     14    58          103 seconds                           ______________________________________                                         *Ignition was made by a hand held flame, i.e. a conventional butane           cigarette lighter.                                                            **The first ignition was made when the test strip had its full 25             millimeter length. For sample 21A, after 39 seconds of burning, 19 mm of      the original 25 mm remained unburned.                                         ***The second ignition was made after the burning strip self extinguished     for the first time. For sample 21A, the second ignition was made when 19      mm of the test strip remained. It took 108 seconds to burn down to an 8 m     length.                                                                  

EXAMPLE 21B

A composition as prepared in Example 21A was prepared to contain theingredients as set forth in Example 21A, but in addition, contained 1.8parts of ultra high molecular weight polyethylene.

The composition was noticeably smoother in its appearance and apparentlymore homogeneous.

After mixing, the composition was pressed into a slab and strips havinga length of over 25 mm and about an equal thickness and width wereprepared to correspond to the dimensions of the test strips of Example21A. From another example in this application, it was known that aquentity of ultra high molecular weight polyethylene about 3 or 4 timesgreater than the polytetrafluoroethylene used in Examples 20A and 20Bwas needed to induce a level of "drying" of the molten, sticky highdensity polyethylene equivalent to that induced by the lesser quantityof PTFE.

Nevertheless, 1.8 parts of ultra high molecular weight polyethylene wereincluded in the composition of this example. Burn tests were conductedas described in Example 21A and the results obtained are set forth inthe Table below.

    __________________________________________________________________________    TABLE FOR EXAMPLE 21B                                                                  SELF EXTINGUISHMENTS    CUMULATIVE                                            1     2     3     4     BURNING TIME                                 TEST SAMPLE                                                                            mm sec.                                                                             mm sec.                                                                             mm sec.                                                                             mm sec.                                                                             TO REACH 25 mm                               __________________________________________________________________________    21B - 1  18 41 11 83 7  101                                                                              3  109                                                                              113 seconds                                  21B - 2                          113 seconds                                  21B - 3  13 31                    53 seconds                                  (very thin                                                                    sample)                                                                       __________________________________________________________________________

As is evident from the contents of this Table, the results of adding 1.8parts of ultra high molecular weight polyethylene are not uniform forthe three tests made. The average burning time is less than thatreported in Table 21A, but the sample 22B-3 here was a very thin sampleand its burning time is apparently lower than normal.

It should be realized also that unlike polytetrafluoroethylene, ultrahigh molecular weight polyethylene is itself a combustible material sothat the addition of this material to a composition containing 50 partsPVC and 50 parts LDPE actually increases the amount of combustiblecomponent in the resultant interdispersion.

However, from the tests reported in another Example, less UHMWPE wasused in this Example 21B than would be needed to form a more completeinterdispersion.

In this regard, see Example 21C below.

EXAMPLE 21C

The compositions and procedures as carried out in Example 21B wererepeated, but with the exception that instead of 1.8 parts of ultra highmolecular weight polyethylene interdispersing agent as used in Example21B, the amount used in this Example 21C was 3.6 parts or double thatemployed in the previous example.

Three test strips were prepared as described in Example 21A andsubjected to test burning also as described in Example 21A. The testresults are set forth in the Table below.

    __________________________________________________________________________    TABLE FOR EXAMPLE 21C                                                                  IGNITION*                             Cumulative                              FIRST**                                                                              SECOND***                                                                            THIRD FOURTH                                                                              FIFTH SIXTH Burning Time                   TEST SAMPLE                                                                            mm sec.                                                                              mm sec.                                                                              mm sec.                                                                             mm sec.                                                                             mm sec.                                                                             mm sec.                                                                             To 25 mm                       __________________________________________________________________________    21C - 1  19 39  17 49  9  88 8  96 3  105      120 seconds                    21C - 2  18 37  16 47  12 67 8  94 4  133      152 seconds                    21C - 3  18 60  16 65  7  110                                                                              3  128            135 seconds                    __________________________________________________________________________

The test results are interpreted to demonstrate that the interdispersionof PVC and LDPE with the aid of 3.6 parts of UHMWPE is a compositionwhich has a much higher tendency to self extinguish and which has ahigher cumulative burning time than the control Example 21A. This resultis obtained in spite of the fact that the composition of sample 21C has3.6 more parts of combustible hydrocarbon than the control sample 21A.Test sample 21C actually contains 51.7% hydrocarbon and is more flameresistant than the control sample 21A which contains only 50%hydrocarbon. Or, to put it another way, the interdispersed compositionof this Example 21C is more flame retardant because of its demonstratedgreater tendency to self extinguish than the mixed composition ofExample 21A which actually contains more PVC flame retardant.

For control Example 21A, the average cumulative time to burn the 25 mmof the test samples is 108.3 seconds. For test Example 21C, theequivalent average burning time is 135.7 seconds.

In addition, the control samples of Example 21A self extinguished twotimes before burning of the full 25 mm strip was completed. For testExample 21C, the test samples self extinguished five times beforeburning of the full 25 mm strip was completed.

Accbrdingly, this Example 21 demonstrates that improved flame retardancecan be achieved for a composition containing a polymeric flame retardantby forming an interdispersion of the flame retardant polymer with acombustible polymer employing a combustible interdispersing agent.

EXAMPLE 22 HDPE/EPR

The procedure used in the previous Example 21 and similar examples wasemployed again and, in this case, the composition contained 50 parts ofhigh density polyethylene and 50 parts of ethylene propylene rubber(Nordel EPDM 1145). This Example 22 also contained 1.5 parts of FlectolH throughout, as did essentially all other examples which includedpolyethylene.

This example is similar to that of the Example 1 with the exceptionsthat:

(1) the proportions of the high density polyethylene to theethylene-propylene rubber are higher and in this Example 22 are 50 partsof each, and

(2) the fillers which were present in the Example 1 are omitted.

EXAMPLE 22A

The Example 22A was prepared by milling as described in the earlierexamples, had no filler and also had no Teflon 6. No appreciableblending was observed.

EXAMPLE 22B

The Example 22B included Teflon 6 but included no filler. An essentiallyhomogeneous interdispersion was observed to form.

EXAMPLE 22C

The Example 22C included 1.8 parts of Teflon 6 but also included 20parts of Translink clay. The filler dispersed well and easily into thecomposition of Example 22B.

EXAMPLE 22D

The Example 22D included 1.8 parts of Teflon 6 and also 45 parts ofclay. This further amount of clay filler dispersed well into thecomposition of Example 22C.

EXAMPLE 22E

The procedure as described in Example 22B was repeated but the effortwas made to reduce the temperature at which the processing was carriedout. The attempt to gain a lower procesing temperature gained perhaps5°-10° F. in lower processing temperature and was succesful at thislower temperature. The results obtained are essentially the same asthose reported with regard to Example 22B above.

EXAMPLE 23

Linear low density polyethylene was processed on a plastic mill with andwithout Teflon 6. The commercial identification of the linear lowdensity polyethylene was LPX-2.

EXAMPLE 23A

The initial material prepared, identified as sample 23A, did not containany Teflon 6. The mill roll temperature for the processing was about235° F. The linear low density polyethylene had a very sharp meltingpoint at low viscosity and was quite sticky after melting.

A sample of the material was removed from the mill and saved for use inExample 23E.

EXAMPLE 23B

1.8 parts of Teflon 6 were added to the linear low density polyethyleneprocessed according to Example 23A. There was a marked change in theappearance of the material as compared to that of 23A, and there was animprovement in its reology which was similar to the improvement whichoccurs when Teflon 6 is added to high density polyethylene on a mill.

EXAMPLES 23C AND 23D

In Example 23C, 20 parts of the Translink clay were added and blendedwell into the composition. In Example 23D, an additional 25 parts ofTranslink clay and also blended well into the composition.

EXAMPLES 23E and 23F

After the preparation of the first two of these materials, i.e., 23A and23B, they were returned to the mill individually and peroxide was addedand, specifically, 1.4 parts of Vulcup R were added to each of thesamples and the samples were then placed in the press and heated at 350°F. for a period of about 30 minutes to form a pressed cured slab. Theslab was allowed to cool in the pressing apparatus through the internalcooling of the press.

The tensile and elongation properties of slabs formed for Examples 23Eand 23F were measured and are included in the table for this example.

    ______________________________________                                        TABLE FOR EXAMPLE 23                                                                                23E   23F                                               ______________________________________                                        Linear low density polyethylene,                                                                      100     100                                           sold by Exxon Chemical under the                                              trade designation LPX-2                                                       Antioxidant additive, polymerized                                                                     1.5     1.5                                           trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the                                             trade designation Flectol H                                                   Peroxide crosslinking agent, sold                                                                     1.4     1.4                                           by Hercules Company under the trade                                           designation Vulcup R                                                          Polytetrafluoroethylene powder                                                                        --      1.8                                           supplied by DuPont under the trade                                            designation Teflon 6                                                          Mill mixed @ 235° F. mill temperature                                  Cured @ 350° F. for 30 minutes and cooled                              under pressure MAT #33666                                                     Original Tensile, psi   2826    3358                                          Original Elongation, %  476     643                                           ______________________________________                                    

EXAMPLES 24A, 24B, 24C and 24D

The procedure used in the Example 23 was repeated but, in this case,instead of using 100 parts of linear low density polyethylene, 100 partsof ethylene propylene rubber and, particularly, the Nordel 1145, wereemployed. The compositions 24A, 24B, 24C and 24D were prepared as in theExample 23.

EXAMPLES 24E, 24F, 24G and 24H

This was followed by the addition of 1.4 parts of Vulcup R to each ofthese samples and the heat curing of the samples into a slab asdescribed in the above examples.

Tensile and elongation of Samples 24E and 24F were measured and aregiven in the Table for this example. Both the tensile and elongation ofthe crosslinked EPR were increased about 50% by the addition of thefibrous PTFE.

    ______________________________________                                        TABLE FOR EXAMPLE 24                                                                                 24E  24F                                               ______________________________________                                        EPDM rubber sold by E. I. Du Pont                                                                      100    100                                           under the trade designation                                                   Nordel 1145                                                                   Antioxidant additive,    1.5    1.5                                           polymerized trimethyl                                                         dihydroquinoline, sold by                                                     Monsanto Chemical Corp. under                                                 the trade designation Flectol H                                               Peroxide crosslinking agent,                                                                           1.4    1.4                                           sold by Hercules Company under                                                the trade designation Vulcup R                                                Polytetrafluoroethylene powder                                                                         --     1.8                                           supplied by DuPont under the                                                  trade designation Teflon 6                                                    Mill mix @ 235° F. mill temperature                                    Cured @ 350° F. for 30 minutes and cooled                              under pressure MAT #33666                                                     Original Tensile, psi    287    428                                           Original Elongation, %   206    316                                           ______________________________________                                    

EXAMPLE 25 LLDPE/EPR

The composition and procedures described with reference to Example 23and 24 were repeated but, in this case, the polymers which were treatedwere the combination of linear low density polyethylene identified inExample 23 and also the ethylene propylene rubber or EPDM of Example 24which was identified as Nordel 1145.

EXAMPLE 25A

The same sequence of treatment steps was used. The composition ofExample 25A, which was prepared without any Teflon 6, showed a markedcoarseness and roughness at its surface and was distinct in this respectfrom the sample A of Example 23 and from the sample A of Example 24.

EXAMPLE 25B

The Example 25B was prepared by the same procedure as that used inpreparation of 25A, but in this case, contained 1.8 parts of Teflon 6.There was a very marked and distinct improvement in the appearance ofthe sample due to the presence and influence of the Teflon 6 additive.This improvement in appearance was deemed to evidence the formation ofan interdispersion of linear low density polyethylene and ethylenepropylene rubber with the aid of the PTFE, Teflon 6.

EXAMPLE 25C and EXAMPLE 25D

Example 25C involved the addition of 20 parts of Translink clay to thematerial prepared according to Example 25B.

Further, the Example 24D involved the further addition of 25 parts ofTranslink clay to the composition of 25C for a total of 45 parts ofTranslink clay.

EXAMPLES 25E, 25F, 25G and 25H

Each of these samples was returned to the mill at a temperature suitablefor addition of peroxide and 1.4 parts of peroxide, Vulcup R, were addedto each of the samples separately. This was followed by a pressing ofthe samples to heated slabs in a press at 350° F. and for a period of 30minutes, followed by cooling to room temperature.

Test results for sample 25E and for sample 25F were obtained. Theresults evidence a dramatic improvement in tensile properties for thesample 25F containing the fibrous Teflon 6 additive. This improvement isattributed to the presence of fibrous Teflon 6 in sample 25B and also tothe greater homogeneity of the interdispersion of the two polymersinduced by the presence of the fibrous Teflon 6 during the process ofinterdispersing the relatively imcompatible linear low densitypolyethylene with and into the ethylene propylene rubber.

    ______________________________________                                        TABLE FOR EXAMPLE 25                                                                                25E   25F                                               ______________________________________                                        Linear low density polyethylene,                                                                      50      50                                            sold by Exxon Chemical under the                                              trade designation LPX-2                                                       EPDM rubber sold by E. I. Du Pont                                                                     50      50                                            under the trade designation                                                   Nordel 1145                                                                   Antioxidant additive,   1.5     1.5                                           polymerized trimethyl                                                         dihydroquinoline, sold by                                                     Monsanto Chemical Corp. under                                                 the trade designation Flectol H                                               Peroxide crosslinking agent,                                                                          1.4     1.4                                           sold by Hercules Company under                                                the trade designation Vulcup R                                                Polytetrafluoroethylene powder                                                                        --      1.8                                           supplied by DuPont under the                                                  trade designation Teflon 6                                                    Mill mix @ 235° F. mill temperature                                    Cured @ 350° F. for 30 minutes and cooled                              under pressure MAT #33666                                                     Original Tensile, psi   1453    2483                                          Original Elongation, %  426     550                                           ______________________________________                                    

EXAMPLE 26A

Pursuant to the present invention, a composition containing 40 parts ofpolyvinyl chloride together with 40 parts of chlorinated polyethylene,and 20 parts of polyethylene were combined on a mill heated to 220° F.Twenty-five parts of dibasic lead phthalate were also included in thecomposition along with 1.5 parts of Flectol H.

The samples were prepared as described in the above examples and theExample 26A composition was milled without any Teflon 6 additive.

EXAMPLE 26B

A sample 26B was prepared to include precisely the same ingredients inthe same ratios as disclosed for Example 26A. The composition was milledon a mill heated to 270° F. with no Teflon 6 additive.

The difference between the two samples was that the sample 26A wasmilled at a mill roll surface temperature of 220° F., sample 26B wasmilled at a mill roll temperature of about 270° F. The temperature of270° F. mill roll temperature is far below the temperature at whichingredients such as those above would be blended or an attempt would bemade to blend them in commercial manufacture of a product. In fact, thetemperature was approximately 80°-100° F. lower than the temperatureconventionally used in the process of blending of the above composition.

EXAMPLE 26C

Sample 26C was prepared to contain the same ingredients as 26A and 26B,but 26C also contained 1.8 parts of Teflon 6. The composition of 26C wasprepared in the same manner as the 26B composition and was also milledat a mill roll temperature of 270° C.

When sample 26A was observed on the mill, all particles of the PVCconstituent were undispersed. By contrast, the composition of Example26B did show a distinct improvement over that of 26A in that there wassignificant amount of dispersion of the PVC particles in thecomposition.

Nevertheless, it was also apparent that much of the PVC in Example 26Bwas not dispersed.

By contrast, the Example 26C showed a relatively homogeneous compositionwith a good and preferred distribution and dispersion of the ingredientsin one another in the form of a homogeneous interdispersion.

EXAMPLES 26D, 26E and 26F

After milling, each of the compositions were individually removed fromthe mill and were saved and were later individually returned to the milland 1.7 parts of Vulcup R were added to each one. The mill rolltemperature had, in each case, been dropped and was at about 250° F.Each of the compositions was blended until the peroxide constituent wasabsorbed into the composition and it was then removed from the mill andplaced on a press where it was pressed for approximately 30 minutes at350° F. to press and cure each sample. The peroxide cured samples 26D,26E and 26F are those which were initially prepared respectively as 26A,26B and 26C. The sample 26D had a very gray appearance made up of manyfine dark dots and small blue colored areas showing what is deemed to bethe deterioration of the original undispersed polyvinyl chloride.

The slab of example 26E had a distinctly salmon color in contrast withthe gray color of 26D, and did nevertheless evidence many fine, fineparticles of evidently deteriorated PVC from the limited distribution ofPVC which had occured in the composition.

By contrast again, the composition of 26F was smooth and fairlylight-colored, but with no visible evidence of deteriorated PVC evidentto the unaided eye. This example illustrates the interdispersingtogether in a single operation and with a single mixing, of a pluralityof diverse polymer components to achieve a high degree of homogeneity inthe interdispersed ternary polymer composition product where the Teflon6 interdispersing agent is employed.

The above observations are reinforced by the following tensile tests onthe cured slabs:

    ______________________________________                                                    SAMPLE  SAMPLE    SAMPLE                                                      26D     26E       26F                                             ______________________________________                                        Mill Roll Temperature:                                                                      220       270       270                                                       No PTFE   No PTFE   With PTFE                                   Tensile, psi  930       1734      2371                                        Elongation, %  85       130       160                                         ______________________________________                                    

In addition, the accomplishment of this dispersion of PTFE andinterdispersion pf ternary polymer composition of Sample 26F occurs at atemperature which is below the temperature at which the material mightotherwise undergo blending.

It is, of course, evident in the plastics field that any appreciablereduction in the time during which and temperature at which a polymer isexposed during processing is advantageous.

    ______________________________________                                        TABLE FOR EXAMPLE 26                                                                           26D     26E    26F                                           ______________________________________                                        Polyvinyl chloride 40        40     40                                        Chlorinated polyethylene                                                                         40        40     40                                        Polyethylene       20        20     20                                        Polytetrafluoroethylene powder                                                                   --        --     1.8                                       supplied by DuPont under the trade                                            designation Teflon 6                                                          Dibasic Lead phthalate                                                                           25        25     25                                        Antioxidant additive, polymerized                                                                1.5       1.5    1.5                                       trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the                                             trade designation Flectol H                                                   Peroxide crosslinking agent, sold by                                                             1.7       1.7    1.7                                       Hercules Company under the trade                                              designation Vulcup R                                                          ______________________________________                                    

EXAMPLE 27 Concentrates EXAMPLE 27A

A sample of 100 parts natural rubber smoked sheet was placed on a milland Teflon 6 was gradually added to the composition to the point wherethe milling of the composition became poor due to the high level of theTeflon in the natural rubber. This material contained about 6 parts ofthe Teflon at the time when the poor milling was observed for thissample.

EXAMPLE 27B

A sample of 100 parts high density polyethylene was placed on a mill andmilled and Teflon 6 was gradually added to the composition on the millto the point where the milling of the composition became poor due to thehigh concentration of the Teflon. It was observed that approximately 12parts of Teflon 6 could be added to high density polyethylene on themill before the milling was so poor as it was in the case of Example27A.

EXAMPLE 27C

A composition of 50 parts natural rubber and 50 parts of high densitypolyethylene were placed on the mill and were milled in the presence ofTeflon 6. Additions of Teflon 6 were made gradually to determine theextent to which the Teflon 6 could be added without having thecomposition loose its good milling properties. It was found thatapproximately 25 parts of Teflon 6 could be added to the interdispersionon the mill before the composition lost its good milling properties tothe degree also found in the Examples 27A and 27B. On a percentagebasis, the 25 parts of Teflon 6 added to sample 27C amounts to 20% ofthe composition formed.

It is pointed out in this Example 27A that there is a maximum level ofPTFE that can be incorporated into the natural rubber before thecomposition exhibits the poor millability behavior. It was determined inExample 27A to be 6 parts per 100 parts of natural rubber, or 3 parts ofPTFE per 50 parts of natural rubber.

Similarly, the maximum level of PTFE which can be incorporated into thehigh density polyethylene is 12 parts of PTFE per 100 parts of highdensity polyethylene as evidenced in Example 27B. In other words, 3parts of PTFE is the maximum level for 50 parts of natural rubber and 6parts of PTFE is the maximum level for 50 parts of high densitypolyethylene based on the limit of reaching poor millability.

Accordingly, a composition which consists of 50 parts of natural rubberand 50 parts of high density polyethylene should have the maximumincorporable level of PTFE of 9 parts.

Surprisingly and unexpectedly, the composition containing the 50/50parts of natural rubber and high density polyethylene can incorporate 25parts of PTFE before exhibiting the poor millability characteristics.

Clearly, it is suggested that the composition matrix is neither that ofthe natural rubber nor high density polyethylene, but rather somethingquite unique and novel in that it can accept 25 parts of PTFE. It issuggested that an interdispersion of natural rubber and high densitypolyethylene has produced something unexpected.

These conclusions are reached partly on the basis that theinterdispersion of 50/50 natural rubber and high density polyethyleneaccepted about 270% of the PTFE that was expected to be accepted basedon the amount of PTFE which was accepted by the individual materialsseparately and when not part of an interdispersion as provided pursuantto this invention.

EXAMPLE 28A PE/PVC; 80/20

Eighty parts of low density polyethylene were blended on a mill with 20parts of polyvinyl chloride as set forth in the Table for Example 20.1.5 parts of Flectol H and 1.5 parts of triallyl cyanurate were added.The material, which contained no PTFE, was fluxed on the mill togetherwith 10 parts of dibasic lead phthalate until an apparently uniformcomposition was achieved. The sample 28A was taken off the mill and halfwas reserved for Example 28B.

Half of the sample taken from the mill was returned to the mill andfluxed at a lower temperature and 1.7 parts of Vulcup R were added asindicated in the Table.

The product of the fluxing was removed from the mill and pressed at 350°F. for 30 minutes and cooled while in the press. A sample was taken fromthe slab thus prepared and tensile and elongation values were measured.The averages of values are given in the Table below under Example 28A.

EXAMPLE 28B

The half of the sample which had been reserved from Example 28A wasplaced on the mill and 1.8 parts of Teflon 6 were added to the materialon the mill as indicated in the Table for the initial fluxing. Thetemperature was dropped and Vulcup R was added to the extent indicatedin the Table and the fluxing was continued. The milled sample wasremoved from the mill and pressed in a plastic press to a slab at 350°F. for 30 minutes. The tensile and elongation properties were measuredand are shown in the table under Example 28B.

It is evident from comparison of the results obtained with regard toExample 28A, that a dramatic improvement was made ih the tensileproperty and that there was also some improvement also in the elongationproperty simply as a result of the inclusion of the 1.8 parts of Teflon6 in the example.

    ______________________________________                                        TABLE FOR EXAMPLE 28                                                          INGREDIENTS           28A       28B                                           ______________________________________                                        Low density polyethylene, sold by Exxon                                                             80        80                                            Company under the trade designation                                           LD83.6                                                                        Polyvinyl chloride, sold by Goodrich                                                                20        20                                            Company under the trade designation                                           Geon 30                                                                       Antioxidant additive, polymerized                                                                   1.5       1.5                                           trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the trade                                       designation Flectol H                                                         Triallyl cyanurate    1.5       1.5                                           Peroxide crosslinking agent, sold by                                                                1.7       1.7                                           Hercules Company under the trade                                              designation Vulcup R                                                          Polytetrafluoroethylene Powder supplied                                                             --        1.8                                           by DuPont under the trade designation                                         Teflon 6                                                                      Dibasic lead phthalate, sold by                                                                     10        10                                            Associated Lead Corp. under the trade                                         designation Dythal                                                            Original Tensile, psi 1449      2486                                          Original Elnogation, %                                                                              80        210                                           ______________________________________                                    

EXAMPLE 29A LDPE/PP

Approximately 85 parts of low density polyethylene and 3.0 parts ofFlectol H were placed on a mill having a mill roll temperature of 300°F. Fifteen parts of polypropylene pellets (Amoco Avison 10-1016) wereadded. The composition did not blend together. Rather, the polypropylenepellets retained their identity within the molten polyethylene matrixand did not enter into a mingling or blending with the low densitypolyethylene. Half of the composition was then removed from the mill. Notests were made of this composition because of the non-homogeneity ofdistribution of the constituents.

EXAMPLE 29B

1.8 parts of Teflon 6 were added to the remainder of the composition onthe mill prepared as described in Example 29A. The polypropylene pelletsdispersed fairly rapidly into the low density polyethylene to form aninterdispersion which appeared homogeneous and which was removed pendinglowering of mill temperature.

This blend of 85 parts of low density polyethylene and 15 parts ofpolypropylene was rebanded onto the mill rolls at 220° F. and 1.4 partsof Vulcup R were incorporated therein, followed by removal andpress-curing for 30 minutes at 350° F. The tensile and elongation of theslab composition was measured and the results obtained are in the Tablebelow.

An apparently homogeneous crosslinked composition was obtained.

EXAMPLE 29C

100 parts of low density polyethylene, 1.5 parts of antioxidant and 1.8parts of PTFE were milled at 220° F. and 2.5 parts of dicumyl peroxidewere added and milled into the composition. The composition was removedfrom the mill and a pressed slab was prepared by pressing thecomposition at 350° F. for 30 minutes followed by cooling in the press.

Measurements were made of the modulus and tensile and elongation and thevalues determined are set forth in the table for Example 29.

    ______________________________________                                        TABLE FOR EXAMPLE 29                                                                             29B  29C                                                   ______________________________________                                        20% Modulus, i.e., stress in                                                                              1217                                              psi @ 20% elongation                                                          50% Modulus, i.e., stress in                                                                       1700                                                     psi @ 50% elongation                                                          100% Modulus, i.e., stress in                                                                      1700   1453                                              psi @ 100% elongation                                                         200% Modulus, i.e., stress in                                                                      1700   1463                                              psi @ 200% elongation                                                         Ultimate - tensile in psi                                                                          2300   2879                                              Ultimate - elongation in %                                                                          460    379                                              ______________________________________                                    

The composition of Example 29B had substantially higher modulus values,particularly in the low modulus range, and had fairly constant lowmodulus values as is evident from the table for Example 29.

EXAMPLE 30A

Fifty parts of low density polyethylene were placed on a small millwhich had been preheated to a mill roll temperature of about 310° F. Thelow density polyethylene was allowed to heat until pellets showed signsof melting and the polyethylene was banded on the mill and fluxed tothermal equilibrium as had been done for the other examples employingpolyethylene on a mill. 1.9 parts of Flectol H antioxidant were addedand blended into the low density polyethylene, also as carried out inthe other examples employing polyethylene. After the composition hadreached equilibrium, fifty parts of polystyrene were added to the milland gradually worked into the polyethylene which was fluxing on themill. The material had very little cohesiveness but much adhesivenessand tended to stick to the mill, and had to be removed from the millrolls by scraping with the aid of a razor blade.

A generally beige composition which seemed to break very easily by roughhand evaluation was formed as an apparent blend of the two ingredients.The sample was weighed and approximately one-half was retained as asample.

EXAMPLE 30B

The other half was placed back on the 310° F. mill and 1.8 parts ofpolytetrafluoroethylene were incorporated into the material distributedin the material banded on the mill.

While Example 30B was somewhat sticky coming off the mill rolls, it wasvastly improved of Example 30A not only in decreased stickiness, butalso in much better strength for handling.

Also, there was some noticeable difference in the flexibility andstength of the sample 30B as compared to 30A from rough hand testing ofbulk material and of shaved specimens. The tests were very qualitativebut nevertheless yielded some indication of improved physical propertiesof this interdispersion containing Teflon 6, particularly the friabilityof the material.

The cooled sample broke rather cleanly without strong visual evidence tothe unaided eye of an extensive network of fibers in the composition.

    ______________________________________                                        TABLE FOR EXAMPLE 30                                                                              30A    30B                                                ______________________________________                                        Low density polyethylene                                                                            50       50                                             Polystyrene (Fosterene)                                                                             50       50                                             Antioxidant additive, polymerized                                                                   1.9      1.9                                            trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the trade                                       designation Flectol H                                                         Polytetrafluoroethylene powder supplied                                                                      1.8                                            by DuPont under the trade designation                                         Teflon 6                                                                      Solubility in boiling toluene*                                                                      less than                                                                              over 20%                                                             5 min.   undissolved                                                                   after over                                                                    1 hour                                         ______________________________________                                         *See Example 31B                                                         

EXAMPLE 31

It is well known that the cumulative thermal history that the polymericmaterial experiences during the course of its route of preparation,processing and usage limits or impairs the useful life of an articleformed from the material. Accordingly, it is beneficial in terms ofuseful life of a material to have it produced at the lowest optimumprocessing temperature for minimum chain scission and degradation. Inother words, it is preferable to minimize the accumulation of heathistory. Consequently, there is always a need for the improvement ofprocessing operations, such as processing polymeric materials at reducedprocessing temperature. In this connection, see Examples 31A and 31B.

EXAMPLE 31A

The ingredients and procedures used in preparing sample 30A wererepeated for Example 31A except that the mill had an approximate rollsurface temperature of 240°-250° F.

The polystyrene pellets did not show significant indication of meltingor blending into the polyethylene which had been banded on the mill.Rather, there were very wide openings, very large surface irregularitiesor aspersities, clear evidence of the retention of the polystyrene inits pellet form in which it was placed on the mill and only little orvery moderate evidence of the polystyrene being included into thecomposition being banded on the mill. While some of the pellets appearedto be included, that is, to have been enveloped by the polyethylene,they nevertheless showed only the most negligible indication of havingbecome part of or having entered into a single composition. Thecomposition was clearly heterogeneous to the unaided eye.

The material was removed from the mill and divided into equivalenthalves.

EXAMPLE 31B

One-half of the mixture of polystyrene pellets interspersed inpolyethylene which was removed from the mill in Example 31A was returnedto the 240°-250° F. mill and 1.8 parts of the PTFE were incorporated.Rapidly, the polystyrene pellets disappeared into the polyethylenematrix and the composition appeared homogeneous. The composition had agenerally buff or tan color and was easily removed from the mill showingnone of the sticky property of the material which had been processed atthe higher temperature by, especially, Example 30A.

The sample was removed from the mill and formed into a convenient flatpiece.

When the cooled piece was bent, it was noticed that a light areadeveloped along the bend and that the material did not break cleanly asthe material of Example 30B did. In fact, the material appeared to foldin a manner similar to that of a "living hinge". In other words, thefolded portion of the sheet could be folded and unfolded repeatedlywithout resulting in a clean break of the specimen along the fold line.A very extensive network of fibrous architecture was evident at andaround the "living hinge" fold.

This example demonstrated that the temperature at which aninterdispersion can be formed between a mostly glassly polymer such aspolystyrene, and a highly crystalline polymer pursuant to thisinvention, by and with the aid of distributing PTFE in fine fibrous formin the composition, can be significantly below and, in this example, 60°to 70° F. below the temperature at which the materials entered anapparent interdispersion without the aid of the fibrous PTFE.

Since Example 31A never became a blend, it was omitted from theexperiment following. Small strips were cut from the cooled samples ofthe blends represented by Examples 30A, 30B, and 31B, and the stripsweighed, then put into boiling toluene. After 5 minutes, the 30A striphad disintegrated and dissolved, while the 30B and 31B strips resisteddisintegration and dissolution to the extent that after one full hour inboiling toluene, the strips were still discernible and after removalfrom the toluene followed by complete toluene evaporation, the stripsstill had about one-third of original weight. Thus, although 30B and 31Brepresented blending at 240°-250° F. and 310° F., respectively, theorder of polymeric entanglement of the blending aid fibrous PTFE appearsreasonably similar.

    ______________________________________                                        TABLE FOR EXAMPLE 31                                                                               31A  31B                                                 ______________________________________                                        Low density polyethylene                                                                             50     50                                              Polystyrene (Fosterene)                                                                              50     50                                              Antioxidant additive, polymerized                                                                    1.9    1.9                                             trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the trade                                       designation Flectol H                                                         Polytetrafluoroethylene powder supplied                                                                     1.8                                             by DuPont under the trade designation                                         Teflon 6                                                                      Solubility in boiling toluene 20% undis-                                                                    solved after                                                                  more than                                                                     one hour                                        ______________________________________                                    

EXAMPLE 32A LDPE/PEI

Fifty parts of low density polyethylene were fluxed on a mill as inearlier examples, and 1.5 parts of Flectol H were added. Pellets ofpolyetherimide, available commercially under the trade designationULTEM® of General Electric Company, were added to the fluxing lowdensity polyethylene on the mill. The mill roll surface temperature wasapproximately 400° F. After fluxing for a period of time at thistemperature, it became apparent that the polyetherimide did not blendinto the composition. Half of the composition was removed from the milland retained as a sample.

EXAMPLE 32B

To the remaining half of the composition on the mill, approximately 2.5parts of Teflon 6 were added to the fluxing composition. The mill rollsurface temperature was slowly raised to approximately 430° F.,whereupon it was observed that the Ultem pellets which had a generallycylindrical in initial form, were becoming flat and stringing out andbeginning to disappear. Also, a pronounced change in the viscosity ofthe material banded on the mill was noticed, in that it became much morestiff and viscous, indicating that ULTEM® was being interdispersed withpolyethylene. After these observations, the mill temperature wasdecreased gradually to about a mill roll surface temperature of about220° F. At that temperature, the composition which remained banded onthe mill was removed without difficulty and formed into a convenientflat sample.

From visual observation and from the experience in performing thisexperiment, it is estimated that an interdispersion of polyetherimide inpolyethylene was formed with the aid of fibrous PTFE and that the ratioof the constituents was of the order of ten parts polyetherimide to 90parts of polyethylene.

    ______________________________________                                        TABLE FOR EXAMPLE 32                                                                            32A  32B                                                    ______________________________________                                        Polyetherimide, sold by General                                                                   50     50                                                 Electric Company under the trade                                              designation ULTEM ®                                                       Low density polyethylene, sold by                                                                 50     50                                                 Exxon Corp. under the trade                                                   designation LD 83.9                                                           Antioxidant additive, polymerized                                                                 1.5    1.8                                                trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the                                             trade designation Flectol H                                                   Polytetrafluoroethylene powder                                                                    --     2.5                                                supplied by DuPont under the trade                                            designation Teflon 6                                                          Unified composition formed                                                                        none   10 parts poly-                                                                etherimide                                                                    90 parts poly-                                                                ethylene                                           ______________________________________                                    

EXAMPLE 33A LLDPE/PVC; 80/20

Eighty parts of linear low density polyethylene were blended on a millwith 20 parts of polyvinyl chloride. 1.5 parts of Flectol H and 1.5parts of triallyl cyanurate were added. The material was fluxed on millrolls heated to 235° F. together with 10 parts of dibasic lead phthalateuntil an apparently uniform composition was achieved. The sample wastaken off the mill and half was saved for Example 33B. The sample takenfrom the mill was returned to the mill and fluxed at a lower temperatureand 1.7 parts of Vulcup R were added as indicated in the Table for thisExample 33.

The product of the fluxing was removed from the mill and pressed at 350°F. for 30 minutes and cooled while in the press. A sample was taken fromthe slab thus prepared and tensile and elongation values were measured.The averages of values are given in the Table below under Example 33A.

EXAMPLE 33B

The half of the sample which had been reserved from Example 33A wasplaced on the mill and 1.8 parts of Teflon 6 were added to the materialon the mill as indicated in the Table below for the initial fluxing. Thetemperature was dropped and Vulcup R was added to the extent indicatedin the Table and the fluxing was continued. The sample was removed fromthe mill and press cured in a plastic press to a slab at 350° F. for 30minutes. The tensile and elongation properties were measured and areshown in the table under Example 33B.

It is evident from comparison of the results obtained with regard toExample 33A, that a significant improvement was made in the tensileproperty and that there was also some improvement also in the elongationproperty simply as a result of the inclusion of the 1.8 parts of Teflon6 in the composition of Example 33B.

    ______________________________________                                        TABLE FOR EXAMPLE 33                                                          INGREDIENTS           33A       33B                                           ______________________________________                                        Linear low density polyethylene, sold                                                               80        80                                            under the trade designation LPX-2                                             Polyvinyl chloride, sold by Goodrich                                                                20        20                                            Company under the trade designation                                           Geon 30                                                                       Antioxidant additive, polymerized                                                                   1.5       1.5                                           trimethyl dihydroquinoline, sold by                                           Monsanto Chemical Corp. under the trade                                       designation Flectol H                                                         Triallyl cyanurate    1.5       1.5                                           Peroxide crosslinking agent, sold by                                                                1.7       1.7                                           Hercules Company under the trade                                              designation Vulcup R                                                          Polytetrafluoroethylene Powder supplied                                                             --        1.8                                           by DuPont under the trade designation                                         Teflon 6                                                                      Dibasic lead phthalate, sold by                                                                     10        10                                            Associated Lead Corp. under the trade                                         designation Dythal                                                            Original Tensile, psi 2634      3178                                          Original Elnogation, %                                                                              265       295                                           ______________________________________                                    

EXAMPLE 34 PE/EPR; 50/50

This example discloses an attempt to have the polytetrafluoroethyleneinterdisperse low density polyethylene at a lower temperature than isconventionally used for blending or otherwise processing low densitypolyethylene.

EXAMPLE 34A

Ethylene propylene rubber was put on a mill at a surface temperature ofabout 190° F. 1.8 parts of PTFE were added to the composition andinterdispersed into the EPR fluxing on the mill. Polyethylene pelletswere then added to the material which was fluxing on the mill in aproportion of 50 parts of EPR and 50 parts of the low densitypolyethylene.

After the fluxing was efficiently in progress, the temperature of themill was lowered and the material continued to flux on the mill. Thetemperature of the mill was dropped to about 170° F. and the compositionat that point was cohesive enough to permit the addition of 2.1 parts ofbenzoyl peroxide as a powder. The powder dispersed easily into thecomposition fluxing on the mill. The composition which had been bandingon the mill before the addition of the benzoyl peroxide was relativelydry, but nevertheless continued to retain its coherence and continued toflux on the mill in such manner that the benzoyl peroxide could beconveniently introduced into it.

This result is rather unique and unusual in that it permits the additionof the low temperature curing agent to a composition which containedpolyethylene and in which the low temperature curing agent, namelybenzoyl peroxide, could not normally be used.

Following the addition of the benzoyl peroxide, the sample was removedfrom the mill, put into a press and heated for 30 minutes at 350° F. andthen allowed to cool while in the press.

This example is one of a number which illustrates the novel advantage ofmaking possible secondary processing, in this case, benzoyl peroxidecrosslinking, of interdispersed compositions containing ingredientswhich could not previously be processed at such low temperatures.

It is known that low density polyethylene cannot normally be crosslinkedwith benzoyl peroxide because the benzoyl peroxide decomposes at too lowa temperature to be incorporated by fluxing in the low densitypolyethylene.

However, by interdispersing the low density polyethylene with EPDM as aprimary processing step pursuant to this invention, and employingfibrous PTFE to form such an interdispersion, the use of the benzoylperoxide is made feasible because of the unique and novelinterdispersion of the EPDM and low density polyethylene and the lowtemperature at which this interdispersion fluxes when made pursuant tothe present invention.

EXAMPLE 35A PE/Polyester

A mill was heated until its surface temperature was about 400° F. 100parts of low density polyethylene were banded on the mill. Ten parts ofValox were added to the polyethylene banding on the mill. Three parts ofFlectol H were also added as an antioxidant. The Valox pellets wereobserved to undergo no deformation or softening or blending with thepolyethylene. The composition was removed from the mill, placed in aheated compression press at a temperature of 460° F., and kept there for5 minutes. This heating was sufficient to melt the Valox pellets in thecomposition. After the melting of the Valox, the composition was removedfrom the heated press and quickly placed on the mill which stillremained at about 400° F. and milling was continued until the materialreached mill temperature.

The composition was again removed from the mill and put into the hightemperature press at the temperature of 460° F. for a period ofapproximately an additional 5 minutes. After removal from the press, thematerial was again placed directly onto the mill which was in operationand at the temperature of about 400° F. and the material was furthermilled while the temperature of the composition remained above thetemperature of the mill rolls.

This removal from the mill, heating in the high temperature press, andreturn to the mill was repeated twice more.

After these four treatments, the composition on the mill was changedvery little, indicating very little blending had occurred.

EXAMPLE 35B

Example 35A was repeated, except 3.6 parts of Teflon 6 were initiallypresent in the mixture, which presence resulted, after the series ofmillings and hot press heatings as recited in Examples 35A, in anessentially uniform interdispersion of Valox and polyethylene.

EXAMPLE 36 PE/PS; 50/50

A composition of 50 parts low density polyethylene and 50 partspolystyrene were banded on a mill with the aid of 1.8 parts of fibrousPTFE in the manner described in Examples 30B and 31B.

After the composition was well banded and apparently homogeneous at atemperature of about 240° F., 0.5 parts of dicumyl peroxide were addedto the banded composition and interdispersed into the interdispersion ofpolyethylene and polystyrene as a co-grafting agent.

By co-grafting, as used in this application, is meant the inducing of achemical linking of different polymer species as a secondary treatment.The primary treatment of this invention is the interdispersion of twootherwise incompatible polymers, i.e., the interdispersing of lowdensity polyethylene and polystyrene at 240° F.

An ideal co-grafting would be the formation of a chemical bond betweeneach pair or distinct molecules of the interdispersion to further reduceand eliminate the capability of the primary interdispersions to bedissolved by solvents which dissolve one or both components of theprimary blend. As noted elsewhere, for example, with reference to thepolyethylene/polystyrene primary interdispersions of this inventioncontaining 1.8 parts of fibrous PTFE, they resist solution in boilingtoluene and at least partially persist as interdispersions for more then12 times longer than an apparent blend composition prepared at highertemperatures without the fibrous PTFE primary interdispersing agent.

The addition of a co-grafting agent as a secondary treatment pursuant tothis example is to further increase the solvent resistance of theprimary interdispersion of this invention. In this example, the peroxideco-grafting agent was added in an amount less than that usually added tocause full crosslinking in a static system, i.e., crosslinking by whichthe constituents are heated in a given form, as in the form of a wireinsulating sheath or a slab in a press.

Rather, the peroxide was added as a co-grafting agent while the primaryinterdispersion was still being fluxed on a mill at a temperature belowthe decomposition temperature of the peroxide. To induce the co-graftingon a molecular scale, the temperature of the mill and of the primaryblend fluxing on it, was raised to a temperature above the peroxidedecomposition temperature as the primary interdispersion remained bandedon the mill and as the mill continued to flux the primaryinterdispersion.

There was no distinct modification of the appearance of the primaryinterdispersion or of the fluxing of the interdispersion as thedecomposition temperature of the peroxide was reached and passed. Thesample was removed from the mill and saved for evaluation.

EXAMPLE 37 PVC/LDPE; Sioplas; 50/50 EXAMPLE 37A

This example is essentially a repeat of the procedure described withregard to Example 20 in that the composition employed is polyvinylchloride blended with a low density polyethylene (LDPE), except that theLDPE used was a silane-grafted, moisture-curable version knowncommercially under the trade name Sioplas. Because the Sioplas undergoesa different curing mode, no peroxide was added to the blend compositionswhich otherwise followed the procedure of Example 20A. A poorlyintermixed composition resulted with PVC particles distributed in theLDPE.

EXAMPLE 37B

The composition of Example 37A was divided and half was kept and theremainder was returned to the mill as sample 37B.

In preparing the blend 37B, it was observed that 1.8 parts of Teflon 6greatly enhanced the interdispersion of PVC with silane-graftedpolyethylene to form a smooth, apparently homogeneous composition withno apparent evidence of persistant PVC particles. The PVC interdispersedwith the silane-grafted polyethylene in much the same fashion as the PVCwas interdispersed with unmodified polyethylene as in Example 20B.

After the compositions 37A and 37B were prepared, 30 mil thick slabswere compression-pressed out at 400° F. for 10 minutes, followed byallowing the pressed slabs to stand on a laboratory bench for 2 days toallow ambient air moisture to permeate into the slabs. Thereafter,strips were cut from the slabs for samples 37A and 37B, and both stripsshowed good shape integrity after prolonged immersion in boiling tolueneindicating that crosslinking by the grafted silane had occurred.

EXAMPLE 38A PP/Silicone Gum; 50/50

A mill was heated to a mill roll temperature of 330° F. Fifty parts ofsilicone gum, available from General Electric Company under the tradedesignation SE-33, were placed on the mill and 50 parts of polypropylenewere also placed on the mill. 1.5 parts of Flectol H was also added.Essentially no blending of the polypropylene with the silicone gumoccurred.

EXAMPLE 38B

However, when 1.8 parts of Teflon 6 were added to the composition on themill, the polypropylene interdispersed into the silicone gum to form asmooth, apparently homogeneous composition.

EXAMPLE 38C

The procedure of Example 38B was repeated using the silicone gum SE-33and polypropylene in a ratio of 75 parts of silicone gum to 25 parts ofpolypropylene. The initial milling was at the 330° F. mill rolltemperature. When a homogeneous blend had formed with the aid of thefibrous PTFE, the mill roll was lowered to a mill temperature to 230° F.

EXAMPLE 38D

1.4 parts of Vulcup R peroxide were then added to the composition asprepared in Example 38C. The composition was introduced into a press andwas then compression-molded for 30 minutes at 350° F. to give a curedslab.

EXAMPLE 39A and 39B HDPE/PVC; 80/20

The ingredients, i.e., 80 parts polyolefin and 20 parts of PVC togetherwith the other ingredients of the table for Example 33, were combinedaccording to the procedures that were used in Examples 33A and 33B.However, in this Example 39, high density polyethylene (USI MA-778) wasused in place of linear low density polyethylene (LPX-2) of Examples 33Aand 33B.

Mill roll surface temperature of about 260° F. was used in the presentExamples 39A and in 39B. Similar overall outcomes, showing improvementsin Sample 39B over sample 39A due to inclusion of Teflon 6, were foundvisually before and after curing, as well as by physical testing.

For Example 39A without Teflon 6 and corresponding to Example 33A, thetensile and elongation results were 2748 psi and 240%, recpectively. ForExample 39B with Teflon 6, corresponding to Example 33B, the tensile andelongation results were 3095 psi and 300% respectively.

    ______________________________________                                        TABLE FOR EXAMPLE 39                                                          SAMPLE           TENSILE   ELONGATION                                         ______________________________________                                        39A - No Teflon  2748      240                                                39B - With 1.8 parts Teflon                                                                    3095      300                                                ______________________________________                                    

EXAMPLE 40 PS/LDPE Sioplas; 50/50 EXAMPLE 40A

The ingredients and procedure as recited in Example 37A was repeated butwith the exception that 50 parts of LDPE Sioplas was combined with 50parts of polystyrene. The composition was prepared in the absence ofPTFE on a mill having rolls preheated to 250° F. A poorly intermixedcomposition was obtained with PVC particles distributed in the Sioplas.The composition was removed from the mill and half was saved.

EXAMPLE 40B

The remaining half was returned to the mill and 1.8 parts of PTFE wereadded and the composition was fluxed on the mill at 250° F. A wellinterdispersed combination of Sioplas LDPE and polystyrene were formedwith the aid of the PTFE.

The compositions of Examples 40A and 40B were pressed into slabs asdescribed in Example 37 and the slabs were cured. Immersion in boilingtoluene did not result in dissolution of the slab samples.

EXAMPLE 41 LDPE Sioplas/Silicone Gum 50/50

Example 37 was again repeated except that the ingredients used were a50/50 mixture of LDPE Sioplas and GE SE-33 silicone gum, using 220° F.mill roll surface temperature.

EXAMPLE 41A

Without Teflon 6, there was a very low level of any apparent blending.

EXAMPLE 41B

With 1.8 parts of Teflon 6, an interdispersion formed and exhibitedgreater homogeneity, cohesiveness and much better handling properties.

Corresponding slabs were compression pressed at 400° F. for furthercharacterization.

EXAMPLE 42A LDPE/Silicone Fluid; 100/5

One hundred parts low density polyethylene were banded with 1.5 partsFlectol H on a 220° F. mill. Five parts of Viscasil silicone fluid of30,000 centistoke viscosity were then carefully added to the bandedpolyethylene. This added silicone fluid caused the banded material tocrumble apart and fall from the mill rolls. Half of the crumbs weresaved.

EXAMPLE 42B

The other half of the crumbs were put back into the mill nip. 1.8 partsof Teflon 6 were added and amazingly caused a re-agglomeration of thecrumbs into a nicely milling band. The banded composition was removedand allowed to cool to room temperature. On standing, the compositiondisplayed no tendency to exude (bloom) the silicone out of the cooledpolyethylene.

This example demonstrates that it is feasible to interdisperse lowmolecular weight polymeric material with the aid of very moderateamounts of fibrous PTFE and accordingly demonstrates that other lowmolecular weight material can be interdispersed with the aid of moderateamounts of fibrous PTFE as demonstrated by the blending of low molecularweight material of this example.

Judging from the good appearance of the banded material of this example,and from the good appearance of the cooled slab, it was estimated that asubstantially larger amount of the low molecular weight polymer could besuccessfully blended into and retained in the banded higher molecularweight polymer on the mill.

Also, it was estimated that higher concentrates of PTFE could improvethe interdispersability of low molecular weight polymers.

EXAMPLE 42C

The procedure of Example 42A was repeated with 10 centistoke siliconefluid. Crumbling of the banded low density polyethylene and droppingfrom the mill occurred at the 2.5 part level.

EXAMPLE 42D

The crumbs could not be re-agglomerated--even with the addition of 5-and 10-parts Teflon 6 to the crumbs on the mill.

EXAMPLE 42E

The addition of 10 centistoke fluid to polyethylene banded on the millwas tried again, but this time by addition of the fluid to low densitypolyethylene which was milling with the 1.8 parts Teflon 6 alreadyincorporated and dispersed therein. About 3 parts of 10 centistokesilicone fluid were all that could be added before the band fell apartand dropped from the mill.

The applicants estimate that such 10 centistoke silicone fluid is of amolecular weight of about 600-1000. The applicants further estimate thatmolecules or polymers of this order or size and weight is about thelimit that 1.8 parts of Teflon 6 will ensnare or entangle orinterdisperse into an ordinary low density polyethylene polymer matrixand thus permit and enhance combination therewith, which combinationdoes not otherwise occur therewith.

EXAMPLE 43 PS/PVC; 50/50

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend formed from the attemptto blend a binary pair of ingredients on a heated plastic mill as setforth below.

EXAMPLE 43A

An attempt to blend polystyrene and polyvinyl chloride in a 50/50 ratiowithout Teflon 6 was made. Questionable blending and unsatisfactoryhandling behavior were found to occur.

EXAMPLE 43B

1.8 parts of Teflon 6 were added to one-half of the composition ofExample 43A. Satisfactory interdispersing and much improved handlingbehavior were observed for the resulting composition.

EXAMPLE 44 PS/PMA; 50/50

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend formed from the attemptto blend a binary pair of ingredients on a heated plastic mill as setforth below.

EXAMPLE 44A

An attempt to blend polystyrene and polymethylmethacrylate in a 50/50ratio without Teflon 6 was made. No apparent blending took place amd acoarse, non-homogeneous mixture resulted.

EXAMPLE 44B

1.8 parts of Teflon 6 were added to one-half of the composition ofExample 44A and an interdispersion was observed to form havinghomogeneity of appearance.

EXAMPLE 45 PC/PE; 50/50; 75/25

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend formed from the attemptto blend a binary pair of ingredients on a heated plastic mill as setforth below.

EXAMPLE 45A

An attempt to blend Lexan polycarbonate and Valox polyester in a 50/50ratio without Teflon 6 was made. Little, if any, blending progressappeared to take place under the relatively lower temperature conditionsunder which the ingredients were combined on a mill.

EXAMPLE 45B

1.8 parts of Teflon 6 were added to one-half of the composition ofExample 45A and significant interdispersing progress was observed.

EXAMPLE 45C

An attempt to blend Lexan polycarbonate and Valox polyester in a 75/25ratio without Teflon 6 was made. Little, if any, blending or combiningprogress appeared to take place on the lower temperature mill to whichthe ingredients were added.

EXAMPLE 45D

1.8 parts of Teflon 6 were added to the composition of Example 45C andsignificant apparent interdispersing progress was observed.

EXAMPLE 46 PS/PAC; 50/50

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend formed from the attemptto blend a binary pair of ingredients on a heated plastic mill as setforth below.

EXAMPLE 46A

An attempt to blend polystyrene and Delrin polyacetal in a 50/50 ratiowithout Teflon 6 was made. No apparent blending took place.

EXAMPLE 46B

1.8 parts of Teflon 6 were added to the composition of Example 46A andan interdispersion was observed to form.

EXAMPLE 47 PS/PAM; 60/40

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend formed from the attemptto blend a binary pair of ingredients on a heated plastic mill as setforth below.

EXAMPLE 47A

An attempt to blend polystyrene and a polyamid, specifically Nylon 11,in a 60/40 ratio was made without Teflon 6. Blending outcome appeared tobe unsatisfactory, as judged visually and by poor cohesion.

EXAMPLE 47B

1.8 parts of Teflon 6 were added to half of the composition of Example47A and the outcome appeared much improved, especially by showing goodcohesion. It was concluded that an interdispersion was formed betweenthe polystyrene and polyamid, specifically Nylon 11.

EXAMPLE 47C

An attempt to melt Nylon 66 on the available laboratory mill was madebut the nylon did not melt as the melting temperature of this nylon wastoo high.

An effort to blend and to interdisperse with polyethylene did notsucceed. The failure to interdisperse was attributed to the limitedtemperature attainable on the laboratory plastic mill and the relativelyhigh softening temperature of the particular nylon.

As indicated above, an interdispersion was formed with the aid of PTFEbetween polystyrene and the lower melting polyamid, Nylon 11.

EXAMPLES 48A, 48B, 48C, 48D

A low molecular weight polyethylene (MI30 USI FN500) was employed inExample 48A, without Teflon 6, was very soft and tended to be sticky onmilling.

Example 48B, with 1.8 parts of Teflon 6, was significantly firmer andless sticky.

Examples 48C and 48D, which contained 1.8 parts of Teflon 6 as well as20 parts and 45 parts, respectively, of Translink 37 clay wereprogressively firmer and less sticky.

Thus, this invention appears still operable at the low molecular weightrange of FN500 and the effect of the PTFE on the low molecular weightpolyethylene was taken to evidence the susceptibility of thiscomposition to enter into interdispersions with other polymers.

EXAMPLES 48E, 48F, 48G and 48H

Peroxide curing agent was added to each of the above compositions andthe above four compositions were compression molded for 30 minutes at350° F. into cured slabs.

EXAMPLE 49 LDPE/HDPE; 50/50

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend or interdispersionformed from the attempt to blend or interdisperse a binary pair ofingredients on a heated plastic mill as set forth below.

EXAMPLE 49A

An attempt to blend low density polyethylene and high densitypolyethylene in a 50/50 ratio without Teflon 6 was made. Some apparentblending took place though the composition was apparently nothomogeneous.

EXAMPLE 49B

1.8 parts of Teflon 6 were added to half of the composition of Example49A and the formation of an interdispersion was observed having improvedappearance, homogeneity and cohesion.

EXAMPLE 50 CIPE/PP; 50/50

The procedures and apparatus of the prior examples were employed todetermine by visual observation whether a blend or interdispersionformed from the attempt to blend or interdisperse a binary pair ofingredients on a heated plastic mill as set forth below.

EXAMPLE 50A

An attempt to blend chlorinated polyethylene and polypropylene in a50/50 ratio without Teflon 6 was made. No apparent blending took placeand a very coarse mixture of uneven texture with many openings extendingthrough the composition was formed.

EXAMPLE 50B

1.8 parts of Teflon 6 were added to half of the composition of Example50A and the formation of an interdispersion was observed having vastlyimproved appearance, apparent homogeneity and cohesion.

This composition is deemed suitable for use as formed as a jacketingand/or insulating material on wire and cable.

What we claim as new and desire to secure by Letters Patent of theUnited States is:
 1. As a composition of matter, a chemicallycrosslinkable interdispersion of a polyolefin polymer selected from thegroup consisting of:low density polyethylene, high density polyethylene,linear low density polyethylene, ethylene propylene copolymers, ethylenevinyl acetate copolymer, ethylene ethyl acrylate copolymer, and modifiedpolyethylene:with at least one polymer selected from the groupconsisting of polystyrenes; said interdispersion being at leastpartially formed with polytetrafluoroethylene as an interdispersingagent; said interdispersion containing a peroxide crosslinking agent. 2.A composition as defined in claim 1 wherein the polyolefin polymer islow density polyethylene.